[Elenco soci]


Richetta Maria

Ricercatore tempo indeterminato


Università degli Studi di Roma Tor Vergata
richetta@uniroma2.it

Sito istituzionale
SCOPUS ID: 6602085678
Orcid: 0000-0001-5707-4463



Pubblicazioni scientifiche

[1] Ausiello P., Martorelli M., Papallo I., Gloria A., Montanari R., Richetta M., Lanzotti A., Optimal Design of Surface Functionally Graded Dental Implants with Improved Properties, Lecture Notes in Mechanical Engineering, 294-305, (2023). Abstract
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Abstract: Over the past years, a wide range of dental implants has been proposed. In general, the dentists may find the best solutions according to the specific needs of the patients. A variety of factors influences the level of osseointegration and, consequently, the anchorage of the implant to the bone. The stress transfer mechanism along the bone-implant interface depends upon the surface area of the bone-implant contact. Great efforts have been devoted to the design of 3D porous lattice structures with tailored architectural features in order to reduce the implant stiffness as well as to favour bone ingrowth, thus stabilizing the device. Accordingly, the aim of the current study was to provide further insight into the design criteria for dental implants. In particular, starting from a screw implant (Implant A), different concepts of dental implants were developed: i) Implants B1–B5, with lattice shell surrounding a solid core, without thread; ii) Implant C, with lattice structure; iii) Implant D as topography optimized implant. Finite element analysis on the several models of bone-implant provided interesting information in terms of stress distributions in cortical and trabecular bone. Some differences among the implants may be ascribed to the different design criteria.

Keywords: Dental implants | Design criteria | Finite element analysis | Lattice structure | Topography optimization | Topology optimization

[2] Montanari R., Lanzutti A., Richetta M., Tursunbaev J., Vaglio E., Varone A., Verona C., Plasma Carburizing of Laser Powder Bed Fusion Manufactured 316 L Steel for Enhancing the Surface Hardness, Coatings, 12(2), (2022). Abstract
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Abstract: Austenitic stainless steels produced by laser powder bed fusion (L-PBF) are quite interesting materials owing to their specific microstructure consisting of dendrite walls built of dislocations pinned by many nano-oxides that involves significant strengthening without loss of ductility. In this work, different plasma treatments were performed to harden the surface of 316 L steel manufactured by L-PBF. The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), light microscopy (LM) and micro-hardness tests. The experimental results show that all the plasma treatments enhance the hardness of the surface because a C-enriched layer of austenite (S-phase) forms with a thickness up to 25 μm. The plasma gas mixture, consisting of 2.5% (CH4) + 97.5% (H2), resulted in being the most effective and produced a surface hardness (547 ± 27 HV) more than double with respect to that of the untreated material. The treatment temperature was 475 °C, which represents a good compromise between the necessity to avoid the precipitation of M23C6 carbides and the compatibility of treatment time with the industrial practice. Moreover, it has been observed that a 2 μm-thick over-layer of amorphous C forms on the sample surface. The hardness of such over-layer, which depends on the specific treatment and is related to the degree of topological disorder, is generally greater than that of S-phase. The work demonstrates that plasma carburizing is quite effective in hardening the surface of 316 L steel manufactured by L-PBF and further improves its mechanical properties, which are basically superior to those of the same material prepared by conventional processes.

Keywords: 316 L steel | Additive manufacturing | Austenitic stainless steels | Laser powder bed fusion | Low temperature carburizing | Microstructural characterization | Plasma treatment

[3] Cabibbo M., Fava A., Montanari R., Pakhomova E., Paoletti C., Richetta M., Varone A., Grain Orientation and Hardness in the Graded Interlayer of Plasma Sprayed W on CuCrZr, Applied Sciences (Switzerland), 12(4), (2022). Abstract
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Abstract: In this work a W coating was deposited through PS in Ar-H2 atmosphere on a substrate of CuCrZr with an interlayer consisting of gradually changing fractions of Cu and W. The W coating and the interlayer showed good adhesion and no cracks were observed. The hardness of W and Cu along the interlayer was determined by nano-indentation tests and the results showed that a hardness gradient does exist in both the metals. Microstructural examinations suggest that the hardness gradient depends on the texture, which exhibits significant differences along the interlayer: multiplication and movement of dislocations, and localized plasticity under the indenting tip are strongly affected by grain orientation.

Keywords: Coatings | CuCrZr | Functional graded materials | Nano-indentation | Plasma facing materials | Tungsten | X-ray diffraction

[4] Cabibbo M., Fava A., Montanari R., Pakhomova E., Paoletti C., Richetta M., Varone A., Residual stresses in the graded interlayer between W and CuCrZr alloy, Journal of Materials Science, 57(1), 285-298, (2022). Abstract
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Abstract: One of the big challenges for realizing future nuclear fusion reactors is the development of materials able to withstand the high thermal loads and particle fluxes typical of these reactors. This work investigated the residual stresses in a W coating deposited through plasma spraying on a substrate of CuCrZr alloy used in the active cooling system of ITER (International Thermonuclear Experimental Reactor). To this purpose, a graded interlayer consisting of a mixture of W and Cu whose composition gradually changes was deposited between coating and substrate. The W coating-interlayer-CuCrZr substrate system showed good adhesion and no cracks were observed. Residual stresses were investigated by X-ray diffraction (XRD) and nanoindentation tests. Residual stresses in the interlayer have different sign in W (compressive) and in Cu (tensile) and reach their maximum value in the inner part of the interlayer where the relative amounts of the two deposited metals are similar. The main contribution to residual stresses comes from thermal stresses arising when deposited metal and substrate cool together from deposition temperature to ambient temperature owing to the different coefficients of thermal expansion (CTE). The residual stresses measured in W are always below the critical value for crack formation (275 ± 50 MPa) but not negligible. Based on present results, the optimization of deposition temperature seems to be the key for reducing residual stresses in the interlayer.

[5] de Crescenzo C., Richetta M., Martorelli M., Gloria A., Lanzotti A., A Further Investigation Toward the Design of Topology Optimized Solid-Lattice Hybrid Structures for Biomedical Applications, Lecture Notes in Mechanical Engineering, 514-523, (2022). Abstract
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Abstract: Titanium alloys (e.g., Ti6Al4V) have been widely considered for the design of biomedical implants. To avoid stress shielding effects, bone atrophy and implant loosening bone, 3D porous devices with controlled geometry and architecture should represent a promising solution. Several cellular structures were already investigated to obtain a wide range of mechanical properties. Many studies focused on the mechanical performance of diamond and body-centered-cubic. Different kinds of porous and semi-porous femoral stems were also proposed and analyzed. Accordingly, the aim of the current research was to provide further insight into the design of solid-lattice hybrid structures through a two-step process involving the classical and lattice topology optimization. A cementless femoral stem was considered as a case study. The solid isotropic material with penalization (SIMP) was used at varying values of the penalty factor and the effect of the geometrical features of each beam forming the lattice structure was also determined. Differences were found in terms of functional and structural performances according to the selected strategy for the design of the solid-lattice hybrid structures, as a consequence of the material distribution/layout and geometrical features.

Keywords: Biomedical applications | Solid-lattice hybrid structures | Topology optimization

[6] Pakhomova E., Gaudio P., Montanari R., Richetta M., Varone A., Physical simulation of plasma-refractory metals interaction for nuclear applications, Metallurgia Italiana, 113(4), 6-12, (2021). Abstract
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Abstract: Refractory metals are of great interest like plasma facing materials and are candidates for realizing the divertor armours in future nuclear fusion reactors. For this application, the materials must withstand steady state heat loads in the range 5-20 MWm-2 and transient heat load events such as plasma disruptions. This work presents the main results of an extended experimental campaign carried out to simulate the interaction between plasma and some refractory metals like tungsten (bulk and plasma sprayed), W-1%La2O3 and molybdenum. The interaction plasma-material has been simulated by an intense laser pulse and the resulting damage has been analysed taking into account the physical and microstructural differences between the examined materials.

Keywords: Molybdenum | Nuclear fusion reactors | Plasma-refractory metal interactions | Refractory metals | Tungsten | W-1%La O 2 3

[7] Gaudio P., Montanari R., Pakhomova E., Richetta M., Varone A., Surface morphology of refractory metals submitted to a single laser pulse, Materials Science Forum, 1016 MSF, 1526-1531, (2021). Abstract
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Abstract: The work investigates refractory metals (bulk W, W produced via plasma spraying, W- 1% La2O3 and Mo) of interest as plasma facing materials in future nuclear fusion reactors. They have been irradiated by a single Nd:YAG laser pulse to simulate the effects of transient thermal loads of high energy occurring in a tokamak under operative conditions and then examined by SEM observations. In all the materials the laser pulse induces a crater in the central area of laser spot surrounded by a ridge due to movement of molten metal while in a more external area a network of cracks is observed. Diameter and depth of the crater, ablated volume and morphological features of the surrounding area exhibit differences depending on the specific metal, its physical and microstructural characteristics which affect vaporization, melting and heat propagation from the irradiated spot.

Keywords: Laser | Nuclear fusion reactors | Plasma facing materials | Refractory metals | Surface morphology

[8] Arreguin J.L., Montanari R., Ceccarelli M., Ambrogi V., Richetta M., Torres-San-Miguel C.R., Varone A., Design solutions from material selection for rib fixators, Materials Science Forum, 1016 MSF, 303-308, (2021). Abstract
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Abstract: The problems for fixing rib fractures are usually challenged with different rib fixators whose design strongly depends of the material selected for construction. Main issues refer to rib surgery implantation and tissue acceptance for a duration longer than the osteosynthesis. In this paper we discuss how a material selection can strongly suggest different design solutions both in shape of a rib fixator and even constraining or directing the surgical application with an invasive or noninvasive implantation. In particular, in discussing the general issues and specific experiences of the authors the paper illustrates examples of two different solutions under patent request that are dictated by the material whose selection give the design solutions with innovative aspects.

Keywords: Biomaterials | Design | Materials for medicine applications | Rib fixators | Thorax surgery

[9] Richetta M., Varone A., A focus on dynamic modulus: Effects of external and internal morphological features, Metals, 11(1), 1-16, (2021). Abstract
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Abstract: The present work examines the effects of external and internal morphological features on the dynamic elastic modulus and its measure. It consists of two parts. The first part considers the effect of geometrical features of probes and shows the key role of roughness as source of a systematic error leading to the underestimation of the Young’s modulus. The second one is focused on the effect of porosity. Several models which consider the porosity as an ideal regular microstructure and the relative equations describing the Young’s modulus vs. porosity have been reviewed and critically discussed. The values of the relative modulus Er predicted by different models are similar for materials with low porosity (p < 0.2) and isolated pores whereas they strongly diverge if p > 0.2 and interconnected pores are present. Moreover, such models fail to describe the elastic behavior of materials correctly also with low porosity (p ≈ 0.1) such as sintered steels in the case of pores with a preferred orientation and an irregular shape.

Keywords: Dynamic modulus | Geometrical features | Mechanical spectroscopy | Porous materials | Roughness | Sintered steels

[10] Pizzoferrato R., Richetta M., Layered double hydroxides (LDHs), Crystals, 10(12), 1-4, (2020).
[11] Kaciulis S., Bolli E., Varone A., Richetta M., Narducci R., Di Vona M.L., Ciotta E., Pizzoferrato R., Adsorption of heavy metals by layered double hydroxides grown in situ on Al foam, Surface and Interface Analysis, 52(12), 996-999, (2020). Abstract
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Abstract: We investigated the adsorption of heavy metal ions on a nanostructured coating of zinc-aluminum layered double hydroxides (Zn-Al LDHs) grown on aluminum foam by one-step hydrothermal process. This approach aimed to increase the interactive surface and provide a more practical medium for removal of toxic heavy metals from aqueous media. The foam coated with LDH was characterized by using scanning electron microscopy and X-ray diffraction. After immersion in a copper-rich water solution, X-ray photoelectron spectroscopy demonstrated the occurrence of adsorbed copper on the LDH-coated foam with two oxidation states: particles of metallic copper Cu0 with oxidized surface Cu+1. X-ray diffraction showed the presence of Cu+2 in the LDH structure.

Keywords: copper ions | LDH | metal adsorption | SEM | XPS | XRD

[12] Kaciulis S., Mezzi A., Montanari R., Richetta M., Pakhomova E., Varone A., La distribution on the crater surface of W-1%La<inf>2</inf>O<inf>3</inf> produced by a single laser pulse, Surface and Interface Analysis, 52(12), 1093-1097, (2020). Abstract
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Abstract: The W-1%La2O3 alloy has been irradiated by a single laser pulse (λ = 1064 nm) to simulate transient thermal loads of high energy occurring in a tokamak under operative conditions. A zone with a diameter of ~2 mm, namely, much larger than the focal spot, results to be affected by the pulse, and a crater of about 300 μm is observed in its center. La2O3 particles are not present inside the crater. The change of surface morphology is accompanied by elemental redistribution. Multipoint XPS analysis evidenced that the concentration of La is very low in the crater and increases moving toward the border of the affected zone while that of W shows an opposite trend. The composition changes involve only the outmost 5 nm of the sample: through depth profiling, no differences of chemical composition were detected deeper in the alloy between the center and external border of the affected area.

Keywords: laser | microstructure | nuclear fusion reactor | W-La O 2 3 | XPS

[13] Gottschalk J.J., Krumnow E., Lietzau K.H., Foitzik A.H., Richetta M., SpGckle-Visualization of cytotoxic induced cellular displacements, Sensoren und Messsysteme - Beitrage der 19. ITG/GMA-Fachtagung, 552-556, (2020). Abstract
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Abstract: The institute of medicine (US) Committee on Quality of Health Care in America defined that health care should be safe, effective, patient-centered, timely, efficient and equitable. In order to ensure this, scientists analyses the complex development of cancer and novel strategies for a treatment. One common approach is the chemotherapy which is defined as a treatment of cancer using specific chemical agents or drugs that are selectively destructive to malignant cells and tissues. As already mentioned, every kind of cancer and patient is unique which means that an almost successful treatment could be ineffective for the next patient. In most cases, this effect is caused by a chemical resistance against the applied anticancer drug. The formation or increase of unwanted side effects which weaken the patient unnecessarily can result in additional consequences. As a result, a great variety of anticancer drugs nowadays have been primarily evaluated utilizing in vitro or in vivo model. Usually, the efficacy of such complex pharmaceuticals is verified either by minimal inhibitory concentration or with optical microbiological detection methods. However, such an interaction between cells and drugs should only be regarded as an approximation since it is not directly tested on human cells or still needs to be modified for the according detection method. Thus, the samples are often modified and no more natural. A direct adaption of these obtained results are therefore often not possible and not even safe or effective for the patient. One promising approach which could solve these previous mentioned demands, could be the electronic speckle pattern interferometry (ESPI). Alternations of the cells are detected by ESPI, providing false-phase images which are visually evaluated with a color scale. These results are compared regarding the applied drugs, providing better insight on the drug cell-surface interactions. With the help of a false-phase image and the linked color scale as a result of the ESPI the change of the cell during a given time frame are calculated. Afterwards the results to each applied drug are compared and the different effect on the cell is visible.

Keywords: Anticancer drugs | Cellular displacement | ESPI | Interferometry

[14] Montanari R., Pakhomova E., Rossi R., Richetta M., Varone A., Surface morphological features of molybdenum irradiated by a single laser pulse, Coatings, 10(1), (2020). Abstract
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Abstract: Molybdenum (Mo) is considered a plasma facing material alternative to tungsten (W) for manufacturing the divertor armours of International Thermonuclear Experimental Reactor (ITER). Transient thermal loads of high energy occurring in a tokamak during the service life have been simulated through a single laser pulse delivered by a Nd:YAG/Glass laser, and the effects have then been examined through scanning electron microscopy (SEM) observations. An erosion crater forms in correspondence with the laser spot due to the vaporization and melting of the metal, while all around a network of cracks induced by thermal stresses is observed. The findings have been compared to results of similar experiments on W and literature data. The morphology of the crater and the surrounding area is different from that of W: the crater is larger and shallower in the case of Mo, while its walls are characterized by long filaments, not observed inW, because the lower viscosity and surface tension of Mo allow an easier flow of the liquid metal. Most importantly, the volume of Mo ablated from the surface by the single laser pulse is about ten times that of W. This critical aspect is of particular relevance and leads us to conclude thatWremains the best solution for manufacturing the armours of the ITER divertor.

Keywords: Laser | Microstructure | Molybdenum | Nuclear fusion reactors | Surface damage

[15] Richetta M., Ciotta E., Montanari R., Narducci R., Pizzoferrato R., Varone A., Effect of Al substrate microstructure on layered double hydroxide morphology, Journal of Materials Science, 54(19), 12437-12449, (2019). Abstract
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Abstract: Layered double hydroxides (LDHs) are 2D ionic lamellar nanomaterials, which attract increasing interest for applications in different fields. This paper shows that their morphology is strongly affected by the microstructure of the substrate on which they grow. Zn–Al LDHs were grown in the same conditions on Al substrates with different microstructural features obtained from cold-rolled sheets by annealing at 265 °C for increasing soaking time up to 1 h. LDH morphology was then investigated through scanning electron microscopy observations. The homogeneous distribution of petals on the substrate surface mainly depends on grain size distribution. A bimodal grain size distribution in the substrate leads to the formation of petal clusters and a not complete covering of the surface. In the case of grains of large size the nucleation sites are the dislocations forming the walls of the cells, while owing to their low density, the dislocations inside the grains are not a relevant factor in determining the LDH morphology.

[16] Flora F., Almaviva S., Baldacchini G., Batani D., Bollanti S., Bonfigli F., Di Lazzaro P., Francucci M., Gaudio P., Lai A., Letardi T., Mezi L., Montereali R.M., Murra D., Nichelatti E., Poma A., Scafati A., Palladino L., Pikuz T., Reale A., Reale L., Richetta M., Ritucci A., Rydzy A., Vincenti M.A., Zuppella P., X-ray imaging of bio/medical samples using laser-plasma-based X-ray sources and LiF detector, Journal of Instrumentation, 14(10), (2019). Abstract
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Abstract: This contribution to ECPD2019 is dedicated to the memory of Anatoly Faenov. During a period of approximately thirteen years 1994-2006, Anatoly and his wife Tatiana Pikuz (simply "Tania" for friends), accepting the frequent invitations of the National Institute for Nuclear Physics (INFN) and of the ItalianNationalAgency forNewTechnologies, Energy and Sustainable Economic Development (ENEA), cooperated with many Italian research laboratories dedicated to EUV and soft X-ray generation, spread in different towns (L'Aquila, Frascati, Milano, Padova, Pisa, Roma, etc.). In spite of the fact that they could stay in Italy only about one or two months per year, their activity was so intense that more than 50 peer- reviewed publications were generated from their experimental and theoretical work (just considering only the results obtained at L'Aquila and Tor Vergata - Rome Universities and at the ENEA Research Center of Frascati), without mentioning the cultural atmosphere that they stimulated in the field of Science and Humanity. The numerous experimental spectra obtained at ENEA by means of their spherically bent mica spectrometers, together with the corresponding theoretical simulations performed in Moscow, allowed to study the changing role of different excitations mechanisms for various plasma conditions, and to characterize at best the ENEA laser-plasma source for different applications: polychromatic and monochromatic micro-radiography of dried biological samples at 1 keV, soft X-ray contact microscopy (SXCM) of living cells in the water-window spectral region, spectroscopy of hollow atoms, etc. In this memorial paper, the main results of biological samples imaging on lithium fluoride (LiF) detectors, obtained with the ENEA and Tor Vergata University laser-plasma sources, are presented. In particular, the improvement of the micro-radiography and of the SXCM techniques obtained after moving from photoresist detectors and photographic films to lithium fluoride (LiF) detectors are discussed, for both dried and wet biological samples.

Keywords: Plasma diagnostics - interferometry | Plasma generation (laser-produced, RF, x ray-produced) | Spectroscopy and imaging | X-ray detectors

[17] Serra E., Ciora R.J., De Meis D., Richetta M., Plasma enhancement gases (PEGs) separation using a carbon molecular sieve (CMS) membrane, Fusion Engineering and Design, 146, 2438-2441, (2019). Abstract
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Abstract: Plasma enhancement gases (PEGs) (such as: N2, Ne, Ar and other inert gases) are injected into the plasma of several tokamaks in order to reduce the power load over the plasma facing components. The exhaust gas in the tokamak demonstration reactor (DEMO) consists of more than 90% of unburned fuel gas (D and T) and the remaining part will be He, PEGs and impurities. In DEMO reactor it is foreseen to recover the fuel gas and PEGs. For this purpose in this study a carbon molecular sieve (CMS) membrane and its precursor substrate have been tested at a permeation apparatus built at ENEA Casaccia laboratories. Single gas permeances for H2, He, N2 and Ar were measured with a pressure drop across the membranes between 10 Pa up to 140 kPa at room temperature, 144 °C and 250 °C. We found that H2 to N2 selectivity at 250°C is equal to 47.68 while for H2 to Ar is equal to 35.05.

Keywords: Carbon molecular sieve membrane (CMS) | Gas selectivity | Inorganic porous membranes | Permeance | Plasma enhancement gases (PEG) | Tokamak demonstration reactor (DEMO)

[18] De Meis D., Richetta M., Serra E., Louradour E., Low pressure fusion exhaust gases separation, Fusion Engineering and Design, 146, 1665-1669, (2019). Abstract
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Abstract: Plasma enhancement gases (PEGs) (such as: nitrogen, neon, argon and other inert gases) are injected into the plasma of several tokamaks in order to reduce the power load over the plasma facing components. The exhaust gas in the tokamak demonstration reactor (DEMO) consists of more than 90% of unburned fuel gas (D and T) and the remaining part will be He, PEGs and impurities. In DEMO reactor it is foreseen to recover the fuel gas and PEGs. The research focuses to remove the He from fuel gas and PEGs from fusion reactor. For this purpose, six commercial ceramic membranes have been tested at a permeation apparatus built at ENEA Casaccia laboratories. Single gas permeances for H2, He, Ar and air were measured with a pressure drop across the membranes between 10 Pa up to 100 kPa at room temperature. The selectivities found are low except for the 0.5 nm pore size membranes. The membranes have been supplied by Ceramiques Tecniques et Industrielles (CTI SA, France).

Keywords: Ceramic membranes | Gas selectivity | Inorganic porous membranes | Permeance | Plasma enhancement gases (PEG) | Tokamak demonstration reactor (DEMO)

[19] Gloria A., Montanari R., Richetta M., Varone A., Alloys for aeronautic applications: State of the art and perspectives, Metals, 9(6), (2019). Abstract
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Abstract: In recent years, a great effort has been devoted to developing a new generation of materials for aeronautic applications. The driving force behind this effort is the reduction of costs, by extending the service life of aircraft parts (structural and engine components) and increasing fuel efficiency, load capacity and flight range. The present paper examines the most important classes of metallic materials including Al alloys, Ti alloys, Mg alloys, steels, Ni superalloys and metal matrix composites (MMC), with the scope to provide an overview of recent advancements and to highlight current problems and perspectives related to metals for aeronautics.

Keywords: Aeronautic applications | Alloys | Corrosion resistance | Mechanical properties

[20] De Meis D., Serra E., Richetta M., Llosa Tanco M.A., Pacheco Tanaka D.A., Fusion Exhaust Gas Separation with a Carbon Molecular Sieve (CMS) Membrane, InterCeram: International Ceramic Review, 68(4), 14-17, (2019). Abstract
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Abstract: Abstract : The exhaust gas in the future Tokamak demonstration reactor (DEMO) consists of more than 80 % of unburned fuel gas (D and T) with the balance being He, plasma enhancement gases (PEGs), and impurities. In DEMO we plan to recover the fuel gas (D and T) and PEGs. The paper focuses on the removal of He from the fuel gas and PEGs from the fusion reactors. Hence, the aim of the research is to test potential technologies to achieve this goal. In this paper, a carbon molecular sieve (CMS) membrane supplied by Tecnalia (Spain) is tested to remove the He along with D and T whilst retaining the PEGs.

[21] Gloria A., Maietta S., Richetta M., Ausiello P., Martorelli M., Metal posts and the effect of material–shape combination on the mechanical behavior of endodontically treated anterior teeth, Metals, 9(2), (2019). Abstract
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Abstract: The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. Endodontists generally use posts characterized by different materials, sizes, and shapes. Computer-aided design (CAD) and finite element (FE) analysis were taken into account to provide further insight into the effect of the material–shape combination of metal posts on the mechanical behavior of endodontically treated anterior teeth. In particular, theoretical designs of metal posts with two different shapes (conical-tapered and conical-cylindrical) and consisting of materials with Young’s moduli of 110 GPa and 200 GPa were proposed. A load of 100 N was applied on the palatal surface of the crown at 45◦ to the longitudinal axis of the tooth. Linear static analyses were performed with a non-failure condition. The results suggested the possibility to tailor the stress distribution along the metal posts and at the interface between the post and the surrounding structures, benefiting from an appropriate combination of a CAD-based approach and material selection. The obtained results could help to design metal posts that minimize stress concentrations.

Keywords: Computer-aided design (CAD) | Dental materials | Finite element analysis | Image analysis | Mechanical properties | Metal posts

[22] Maietta S., Gloria A., Improta G., Richetta M., De Santis R., Martorelli M., A further analysis on Ti6Al4V lattice structures manufactured by selective laser melting, Journal of Healthcare Engineering, 2019, (2019). Abstract
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Abstract: Mechanical and architectural features play an important role in designing biomedical devices. The use of materials (i.e., Ti6Al4V) with Young's modulus higher than those of natural tissues generally cause stress shielding effects, bone atrophy, and implant loosening. However, porous devices may be designed to reduce the implant stiffness and, consequently, to improve its stability by promoting tissue ingrowth. If porosity increases, mass transport properties, which are crucial for cell behavior and tissue ingrowth, increase, whereas mechanical properties decrease. As reported in the literature, it is always possible to tailor mass transport and mechanical properties of additively manufactured structures by varying the architectural features, as well as pore shape and size. Even though many studies have already been made on different porous structures with controlled morphology, the aim of current study was to provide only a further analysis on Ti6Al4V lattice structures manufactured by selective laser melting. Experimental and theoretical analyses also demonstrated the possibility to vary the architectural features, pore size, and geometry, without dramatically altering the mechanical performance of the structure.

[23] Richetta M., Varone A., Pizzoferrato R., Layered double hydroxides (LDH): Applications of interest to metallurgy, Metallurgia Italiana, 111(2), 5-14, (2019). Abstract
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Abstract: Layered Double Hydroxides (LDHs) are 2D ionic lamellar nano-materials belonging to the group of anionic clays. Their structure consists of positively charged brucite-like layers and intercalated anions. The layered structure, together with the flexibility to intercept different anionic species (both inorganic and organic) in variable compositions has attracted increasing interest. In order to meet specific requirements in very distant fields, considerable efforts are made to tailor the physical/chemical properties of LDHs and to design engineered LDH for several applications among which those related to metallurgical processes and products are of particular interest. This paper presents the characteristics, some preparation routes and reviews the applications of LDH to metallurgy with some examples taken from the experimental research of the author.

Keywords: Alumina refinement | Anticorrosion film | Catalysis | Heavy metal removal | LDH | Nanomaterials | Surface functionalization | Vocs remediation

[24] Angella G., Di Schino A., Donnini R., Richetta M., Testani C., Varone A., AA7050 al alloy hot-forging process for improved fracture toughness properties, Metals, 9(1), (2019). Abstract
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Abstract: The conventional heat-treatment standard for the industrial post hot-forging cycle of AA7050 is regulated by the AMS4333 and AMS2770N standards. An innovative method that aimed to improve toughness behavior in Al alloys has been developed and reported. The unconventional method introduces an intermediate warm working step between the solution treating and the final ageing treatment for the high resistance aluminum alloy AA7050. The results showed several benefits starting from the grain refinement to a more stable fracture toughness KIC behavior (with an appreciable higher value) without tensile property loss. A microstructural and precipitation state characterization provided elements for the initial understanding of these improvements in the macro-properties.

Keywords: Al alloys | Mechanical properties | Warm working

[25] Richetta M., Varone A., Mattoccia A., Medaglia P.G., Kaciulis S., Mezzi A., Soltani P., Pizzoferrato R., Preparation, intercalation, and characterization of nanostructured (Zn, Al) layered double hydroxides (LDHs), Surface and Interface Analysis, 50(11), 1094-1098, (2018). Abstract
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Abstract: The term layered double hydroxides (LDHs) is used to define synthetic or natural lamellar hydroxides with 2 or more kinds of metallic cations in the main layers, and hydrated interlayer domains, containing anionic species. Layered double hydroxides, also known as hydrotalcite materials, have attracted considerable interest from both industry and academia. They are interesting for their intercalation properties as they are capable of accommodating complex organic molecules. Therefore, they find applications in various fields such as separation technology, catalysis biomedical science, and nanocomposite material engineering. First of all 4, in the context of this work, we present 4 samples of (Zn, Al) LDHs, representative of the 2 hosted anions (Cl− and NO3−), prepared with a simple single-phase hydrothermal technique, using Zn salt as a precursor, deposited on sheets of Al, active as reagent and as a substrate. These preliminary samples, grown for 6 and 24 hours, were intercalated with spermidine and putrescine. Later, (Zn, Al) LDH powders obtained by coprecipitation and intercalated with amino acid cysteine were studied. The properties of LDH nanoplatelets were analysed by surface-sensitive techniques. X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and possibly ultraviolet photoelectron spectroscopy (spectroscopy techniques) have been exploited to investigate the composition of the samples. The structure of LDHs was inspected by X-ray diffraction, whereas the morphology was investigated by scanning electron microscopy.

Keywords: cysteine intercalation | layered double hydroxides | LDH | SEM | XPS | XRD

[26] Maizza G., Montanari R., Richetta M., Varone A., Kaciulis S., Mezzi A., Soltani P., Surface phenomena during the early stage of liquid phase SPS of a mixture of coarse WC and Ni-alloy particles, Surface and Interface Analysis, 50(11), 1072-1076, (2018). Abstract
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Abstract: The tool industry strongly demands more economical, high-performance, healthy, and ecological Co-free WC-based composites. Nickel is considered the optimal substitute of Co in WC-based cermets to attain nearly comparable, if not superior properties in terms of wear resistance and fracture toughness. The combination of WC-Ni with spark plasma sintering (SPS) process may represent a key factor to enhance the properties of future WC-Ni composites. This work aims at studying the early stage of liquid phase sintering of a WC-Ni-alloy powder mixture made of coarse spheroidal WC (80 vol%) and Ni-brazing alloy (20 vol%) particles during low pressure (16 MPa) pulsed SPS. Liquid phase phenomena were investigated both morphologically and analytically by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results reveal that the interface reaction between the liquid Ni and WC particles causes the formation of an outer reaction shell within the WC particles, which is an Ni-W solid solution. Most of necks originated between WC particles were favored by the presence of such reaction shell without any liquid interlayer. A relevant presence of graphitic carbon was observed over the surface of WC particles. The larger atomic W2C/WC ratio in the initial WC powder decreased in the compact after SPS owing to the stabilization reaction between W2C and carbon diffusing across the reaction shell.

Keywords: liquid phase sintering | necking phenomena | Ni-brazing alloy | SPS | WC-Ni composite | XPS

[27] Kaciulis S., Soltani P., Mezzi A., Montanari R., Lapi G., Richetta M., Varone A., Barbieri G., Oxidative treatment effect on TiH<inf>2</inf> powders, Surface and Interface Analysis, 50(11), 1195-1199, (2018). Abstract
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Abstract: Titanium hydride (TiH2) is a brittle powder, which is highly reactive when exposed to heat or strong oxidizers. Namely due to its high reactivity, TiH2 powder is widely applied in pyrotechnics, initiator squibs, and igniters. All the industrial applications of TiH2 are based on its decomposition and consequent hydrogen release. The surface of TiH2 powders has been analysed after different heat treatments in air realized by changing time and temperature. Hydrogen release during heating was investigated by temperature programmed desorption, whereas the crystalline phases were examined by X-ray diffraction. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical states of the surface layers of the treated TiH2 particles. The oxide thickness after different heat treatments was determined by using the XPS depth profiling. The XPS results revealed the presence of Ti3+ and Ti4+ species on the TiH2 surface. The thickness of titanium oxide layer on the TiH2 particles was estimated from the XPS depth profiles. In general, this work explains the result of an experimental campaign directed to study the effect of various heat treatments on phase transformation and surface structure of TiH2 in relation to hydrogen desorption.

Keywords: heat treatment | oxidation | titanium hydride | TPD | XPS | XRD

[28] De Meis D., Serra E., Tosti S., Richetta M., Tati A., Bruni G., Ceramic Membranes for the Separation of Plasma Enhancement Gases, InterCeram: International Ceramic Review, 67(6), 8-13, (2018). Abstract
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Abstract: Low and medium Z impurity seeding gases, or plasma enhancement gases (PEGs) will be injected into the plasma of a Tokamak to convert the plasma thermal energy to ultraviolet and soft X-ray radiation. Possible PEGs are nitrogen, neon, argon, xenon and other inert gases. for the exhaust processing system of the demonstration fusion reactor (DEMO), the use of inorganic membranes was recently taken into consideration. Two commercial ceramic membranes (produced by Atech Innovations GmbH, Germany) were tested at a permeation apparatus built at ENEA Casaccia laboratories. Single gas permeances for H2, He, Ar and N2 were measured with a pressure drop across the membranes between 10 Pa up to 130 kPa at room temperature. For both membranes the permeance order follows the Knudsen regime. The Knudsen permeance measured for the two membranes are on the order of 10−7–10−8. The selectivities found are low (similar to ideal Knudsen).

Keywords: ceramic membranes | DEMO | gas selectivity | permeance | plasma enhancement gases

[29] Pizzoferrato R., Ciotta E., Ferrari I.V., Narducci R., Pasquini L., Varone A., Richetta M., Antonaroli S., Braglia M., Knauth P., Di Vona M.L., Layered Double Hydroxides Containing an Ionic Liquid: Ionic Conductivity and Use in Composite Anion Exchange Membranes, ChemElectroChem, 5(19), 2781-2788, (2018). Abstract
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Abstract: Zinc-aluminum layered double hydroxide (LDH) containing an ionic liquid, 1-butyl-3-methylimidazolium hydrogen sulfate (BmimSO4), has been synthesized by a co-precipitation method. This strategy enabled the intercalation of the ionic liquid (IL) into the interlamellar space of LDH with the aim of increasing the ionic conductivity and reducing its dependence on water content. Pure and IL-intercalated LDHs have been characterized by Fourier-Transform Infrared (FTIR) spectroscopy and X-ray diffraction. Electrochemical Impedance Spectroscopy (EIS) measurements showed that the addition of IL enhanced the ionic conductivity of LDH by a factor of 15 at low humidity and by a factor of 9 at high humidity conditions. As a possible application, LDHs were dispersed as a guest filler in a composite anion exchange membrane (AEM) based on polysulfone-DABCO. In this case, the addition of IL remarkably improved the ionic conductivity of the membrane from 1.0 ⋅ 10−9 to 2.4 ⋅ 10−7 S/cm at low humidity. At high humidity, the membranes reached a conductivity of 25 mS/cm at 25 °C in OH form. Stability tests of composite AEM confirmed the positive effect of LDH nanoparticles.

Keywords: ionic conductivity | ionic liquids | materials science | polysulfone-DABCO | zinc-aluminium layered double hydroxide

[30] De Meis D., Richetta M., Serra E., Microporous inorganic membranes for gas separation and purification, InterCeram: International Ceramic Review, 67(4), 16-21, (2018). Abstract
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Abstract: The importance of inorganic membranes for gas separation and purification is analyzed. Although the cost of inorganic membranes is higher than that for polymeric membranes, they have higher permeance, selectivity and better resistance to higher pressure and temperature. The main materials used for porous inorganic membranes are alumina (Al2O3), silica (SiO2), zirconia (ZrO2), zeolite and carbon. Ceramics are compounds of metallic and non-metallic elements. They generally have a macroporous support, an intermediate layer and a small porous top layer. Because the Knudsen gas separation regime has a very low selectivity, various membrane surface modification techniques have started to be experimented with at a number of laboratories. The research focuses on materials that exhibit molecular sieving properties, such as silica, zeolites, MOFs (metal-organic frameworks), graphene and carbon. Finally, gas transport mechanisms through porous membranes are summarized.

Keywords: Ceramic membranes | Gas permeance mechanism | Gas separation | Inorganic porous membranes

[31] Gaudio P., Montanari R., Pakhomova E., Richetta M., Varone A., W-1% La<inf>2</inf>O<inf>3</inf> submitted to a single laser pulse: Effect of particles on heat transfer and surface morphology, Metals, 8(6), (2018). Abstract
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Abstract: W-1% La2O3 has been irradiated by a single laser pulse (λ = 1064 nm, pulse duration τ ≈ 15 ns, pulse energy Ep ≈ 4 J, spot size Φ = 200 µm, surface power density I = 8.5 × 1011 W·cm−2) to simulate the effects of transient thermal loads of high energy occurring in a tokamak under operative conditions. The samples have been then examined by scanning electron microscope (SEM) observations to investigate erosion effects and surface morphological features. A surface depression forms in the spot central area surrounded by a ridge due to the movement of molten metal. Owing to the burst of gas bubbles, hemispherical cavities of about 10 µm and deposited droplets are observed in the ridge while the zones surrounding the ridge thermal stresses arising from fast heating and successive cooling produce an extended network of micro-cracks that often follow grain boundaries. The results are discussed and compared to those obtained in a previous work on pure bulk W.

Keywords: Laser | Microstructure | Nuclear fusion reactors | W-1% La O 2 3

[32] Maizza G., Pero R., Richetta M., Montanari R., Continuous dynamic recrystallization (CDRX) model for aluminum alloys, Journal of Materials Science, 53(6), 4563-4573, (2018). Abstract
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Abstract: The control of a microstructure, during and after hot forming, is crucial to tailor optimum mechanical properties for specific applications. Recrystallization is a key process which may contribute to a great extent to microstructure development. Dynamic recrystallization is becoming an attracting research area to investigate novel hot forming routes in order to maximize the performance of aluminum products while shortening the time required for manufacturing. A continuous dynamic recrystallization (CDRX) mathematical model was developed by Gourdet–Montheillet (GM) to predict the inherent phenomena of an AA1200 alloy. In the present work, the original GM model has been extended and applied to study CDRX in a 5052 aluminum alloy. The proposed model embodies a solid solution and second phase strengthening, through newly estimated kinetic factors and a kinetic constant, respectively, to discern the CDRX behavior of 5052 aluminum alloy compared to AA1200. The latter kinetic constant relies on the Kocks–Mecking–Estrin (KME) theory. The input law of the fraction of high angle boundaries (fHAB), as a function of strain (ε) (but independent of temperature and strain rate), is defined as the best fitting function of the experimental data. The results are presented in terms of stress–strain curves, dislocation density, and (sub) grain size, as these are important design parameters from an industrial and engineering viewpoint. The model has been validated successfully, from both a qualitative and quantitative point of view, against various literature data sources and tests (e.g., hot compression, hot plane strain compression, and equal channel angular pressing) pertaining to the 5052 alloy and other similar Al–Mg alloys.

[33] Gottschalk J.J., Stollfuß C., Lietzau K.H., Foitzik A.H., Richetta M., Conceptual study for long-term monitoring of chemotherapeutic induced cell reactions by ESPI, Technisches Messen, 85(2), 111-118, (2018). Abstract
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Abstract: During the last years, various approaches on an individualized drug therapy for benign cells have been researched. However, due to the complex topic a universal approach has not been found up until this point. Commonly, the effect of cytotoxic drugs on benign cells is in most cases the same compared to regular cells while the actual effect on patient still can't be predicted. In order to reduce unwanted side effects or unspecific drug reactions a test system for patients which allows to analyse the interaction between cytotoxic agents and the targeted cells is needed. Furthermore, this should also include an adequate measurement system which is capable to work in a natural environment and without any additional preparation. In terms of this work, a first proof of concept with different benign cells and cytotoxic agents is presented while monitoring the obtained displacement using electronic speckle pattern interferometry (ESPI).

Keywords: Chemotherapeutika | ESPI | Interferometrie | zelluläre Verformungen

[34] Gottschalk J.J., Krumnow E., Lietzau K.H., Foitzik A.H., Richetta M., Speckle-Visualization of cytotoxic induced cellular displacements, Sensoren und Messsysteme - 19. ITG/GMA-Fachtagung, 552-556, (2018). Abstract
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Abstract: The institute of medicine (US) Committee on Quality of Health Care in America defined that health care should be safe, effective, patient-centered, timely, efficient and equitable. In order to ensure this, scientists analyses the complex development of cancer and novel strategies for a treatment. One common approach is the chemotherapy which is defined as a treatment of cancer using specific chemical agents or drugs that are selectively destructive to malignant cells and tissues. As already mentioned, every kind of cancer and patient is unique which means that an almost successful treatment could be ineffective for the next patient. In most cases, this effect is caused by a chemical resistance against the applied anticancer drug. The formation or increase of unwanted side effects which weaken the patient unnecessarily can result in additional consequences. As a result, a great variety of anticancer drugs nowadays have been primarily evaluated utilizing in vitro or in vivo model. Usually, the efficacy of such complex pharmaceuticals is verified either by minimal inhibitory concentration or with optical microbiological detection methods. However, such an interaction between cells and drugs should only be regarded as an approximation since it is not directly tested on human cells or still needs to be modified for the according detection method. Thus, the samples are often modified and no more natural. A direct adaption of these obtained results are therefore often not possible and not even safe or effective for the patient. One promising approach which could solve these previous mentioned demands, could be the electronic speckle pattern interferometry (ESPI). Alternations of the cells are detected by ESPI, providing false-phase images which are visually evaluated with a color scale. These results are compared regarding the applied drugs, providing better insight on the drug cell-surface interactions. With the help of a false-phase image and the linked color scale as a result of the ESPI the change of the cell during a given time frame are calculated. Afterwards the results to each applied drug are compared and the different effect on the cell is visible.

Keywords: anticancer drugs | cellular displacement | ESPI | Interferometry

[35] Barbieri G., Cognini F., Bonaiuto V., Montanari R., Richetta M., Varone A., Laser beam welding of in792 ds superalloy, Materials Science Forum, 941 MSF, 1149-1154, (2018). Abstract
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Abstract: The main purpose of the investigation is to develop reliable methods to repair IN 792 superalloy components by Laser Beam Welding (LBW). The jet engine structural components made of nickel-base superalloys are subjected to high stresses and severe environmental, therefore crack may occurs during in-service life. Considering the high cost of this components they are often repaired by welding. Welds must be made: (i) by altering as little as possible the original microstructure; (ii) without introducing in the molten (MZ) and heat affected (HAZ) zones relevant residual stresses; (iii) without producing cracks in MZ and HAZ; (iv) without massive chemical segregation; (v) without elemental diffusion changing the composition of γ and γ’ phases. LBW has been used to realize seams on 2mm-thick plates of directionally solidified (DS) IN792 superalloy. An Yb fiber laser has been employed in present experiments and the molten pool was shielded from oxidation through a patented equipment. A grid of samples has been prepared by varying the pass speed v from 1 to 2.0 m/min with pre-heating temperature of 200 °C. The microstructural changes occurring in the microstructure of molten zone (MZ) and heat affected zone (HAZ) have been investigated by optical and scanning electron microscopy (SEM) observations and energy dispersion spectroscopy (EDS).

Keywords: INS 792 | Laser Welding | Nickel superalloy

[36] De Sanctis M., Fava A., Lovicu G., Montanari R., Richetta M., Testani C., Varone A., Temperature dependent mechanical behavior of ods steels, Materials Science Forum, 941 MSF, 257-262, (2018). Abstract
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Abstract: An oxide dispersion strengthened (ODS) ferritic steel with nanometric grain size has been produced by means of low-energy mechanical alloying (LEMA) of steel powder (Fe-14Cr-1W-0.4Ti) mixed with Y2 O3 particles (0.3 wt%) and successive hot extrusion (HE). The material has equiaxed grains (mean size of 400 nm) and dislocation density of 4 x 1012 m-2, and exhibits superior mechanical properties with respect the unreinforced steel. The mechanical behavior has been compared with that of ODS steels prepared by means of the most common process, high-energy mechanical alloying (HEMA), consolidation through hot isostatic pressing (HIP) or hot extrusion (HE), annealing around 1100 °C for 1-2 hours, which produces a bimodal grain size distribution. The strengthening mechanisms have been examined and discussed to explain the different behavior.

Keywords: Low-energy mechanical alloying | Mechanical properties | Nanostructure | ODS steel | Strengthening mechanisms

[37] Schneider S., Selig M., Keil V., Lehmann M., Foitzik A.H., Casalboni M., Richetta M., Development of a smartphone based reader for the quantitative analysis of lateral flow assays, Materials Science Forum, 941 MSF, 2522-2527, (2018). Abstract
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Abstract: Smartphones are developing into all-purposes devices. In the present work, the employment/application of smartphones as medical devices in home care and point-of-care (POC) diagnostics are investigated in the analysis of Lateral Flow Assays (LFA). A smartphone-based LFA reader was developed for the quantitative analysis of D-Dimer – a biomarker indicating e.g. thrombotic event or danger of embolism. The proof-of-concept has been shown with multiple smartphones in establishing: • Optimal dimensions of the LFA cell of 72.11mm distance of smartphone to D-Dimer test leading to a coefficients of variances (CV) between 0.8% and 4.2% • Inter-device investigations: CVs around 13.5%; a limit of detection (LOD) of 100ng/ml (DDU) D-Dimer • Inter-smartphone investigations: CV about 16%, a limit of detection (LOD) at 66.4ng/ml (DDU) • Calibrations: CV and LOD of three smartphones are comparable to the commercial available LFA reader Further development to put the multiple smartphone-based LFA reader on the market.

Keywords: App | Home-Care | Lateral Flow Assay | LFA Reader | Point-Of-Care (POC) | Quantitative analysis | Smartphones

[38] Gloes F., Boehme A., Liebscher T., Zinn S., Richetta M., Foitzik A.H., Analyte tracking for novel bio-applications, Materials Science Forum, 941 MSF, 2454-2457, (2018). Abstract
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Abstract: Modern cell culture as well as sophisticated bio-applications involve complex biochemical processes, which are required to induce growth, product development or material degradation. Tracking the reaction processes inside the application presents a major challenge due to its complexity. The development of new analysis and tracking mechanisms for such application presents a solution to fully understand the process. In addition, the applied sensors are required to monitor the reactions enable a live tracking of the process. Furthermore, this gives the opportunity to influence and manipulate reactions to further enhance the application of the process. Possible analytes for tracking during processes can be chemical origin such as glucose, cytokines, antibiotics and growth factors, which are included in the culture medium. Based on the complexity of the culture or bio-application the sensor tracking mechanism has to be adapted to ensure full process control. A variety of different approaches can be used for the tracking mechanism.

Keywords: Bio application | Polymer materials | Sample tracking

[39] Gottschalk J., Krumnow E., Lietzau K.H., Foitzik A.H., Richetta M., Monitoring of cytotoxic induced cellular displacements by utilizing electronic speckle pattern interferometry, Materials Science Forum, 941 MSF, 2513-2517, (2018). Abstract
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Abstract: Modern medical science delivers through innovative chemical or mechanical/physical means new strategies to treat patients mildly and fight diseases accurately. In line with this development a screening procedure for tissue samples under usage of the electronic speckle pattern interferometry is developed at the University of Applied Science Wildau. The paper at hand provides the corner stone for such a procedure in form of an incubation system that is adapted to the properties of an electronic speckle pattern interferometer and allows the incubation as well as study of samples over time. As a result the developed system can regulate its own temperature and is constructed for use in an electronic speckle pattern interferometry (ESPI) setup. Its design allows a simple modular approach for further development.

Keywords: Advance Manufacturing | Applications | Fabrication | Processing

[40] De Sanctis M., Lovicu G., Ishak R., Richetta M., Varone A., Novel methodology for the selection, dosing and on-line control of corrosion inhibitors for industrial acid pickling, Materials Science Forum, 941 MSF, 1698-1704, (2018). Abstract
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Abstract: A novel methodology based on electrochemical hydrogen permeation tests is proposed to study the efficiency of commercial inhibitors for industrial acid pickling of iron and mild steels. Weight loss measurements and hydrogen permeation tests have been carried out in order to compare the sensitivity of different techniques to variations of low inhibitor dosages. It has been found a close dependence between low amounts of filming inhibitors and hydrogen uptake in the metallic surface with related permeation currents. The high sensitivity of permeation currents may be very useful to establish and also control the optimum amount of active substances in industrial pickling baths, with related cost savings. The implementation of the proposed methodology to improve the control of industrial pickling plants is also envisaged, since it would be possible to improve both sensitivity and time response of experimental permeation curves.

Keywords: Acid pickling | Hydrogen permeation | Inhibitors

[41] Barbieri G., Bifaretti S., Bonaiuto V., Cognini F., Moncada M., Montanari R., Pipolo S., Richetta M., Varone A., Portable system for the measure of efficiency in arc welding processes, Materials Science Forum, 941, 2384-2389, (2018). Abstract
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Abstract: In recent years, the monitoring of the energy consumption in the industrial processes shows a growing interest due to its strong fallout on environmental pollution and environmental sustainability. On this purpose, this paper deals with the design of a portable Digital Acquisition system (DAQ) tailored for monitoring the energy consumption in different classes of welding machines. The proposed system is a multichannel DAQ able to measure the overall power consumption at the input of the machine (including those relative to the secondary equipment present in the welding process as gas pumps, chillers, etc.) together with some other physical quantities in output (which depend on the features own of the welding machine). The results of these measurements will be deeply investigated and, by a proper metallurgical analysis, related to the mechanical characteristics of the welted joint. Some results on preliminary measures performed on a Tungsten Inert Gas (TIG) welding machine in a real industrial welding process will be shown in the paper.

Keywords: Efficiency | Welding Machines

[42] Ciotta E., Pizzoferrato R., Di Vona M.L., Ferrari I.V., Richetta M., Varone A., Increasing the electrical conductivity of layered double hydroxides by intercalation of ionic liquids, Materials Science Forum, 941, 2209-2213, (2018). Abstract
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Abstract: Zinc-aluminum layered double hydroxide (LDH) has been synthesized and intercalated with two ionic liquids, 1-butyl-3-methylimidazolium hydrogen sulfate (BmimHSO4) and tetramethylammonium hydroxide pentahydrate (TMA 5H2O) in order to increase the ionic conductivity of the composite material. Pure and IL-intercalated LDHs have been characterized by X-ray diffraction, Fourier-Transform Infrared spectroscopy and Electrochemical Impedance Spectroscopy. The addition of BmimHSO4 enhanced the ionic conductivity of LDH by a factor of 9 at high humidity conditions, which are promising results for applications to composite electrodes in fuel cells or batteries.

Keywords: Conductivity | Ionic liquids | Layered double hydroxides (LDHs)

[43] Gambini M., Montanari R., Richetta M., Stilo T., Varone A., Vellini M., Hydrogen release from oxidized titanium hydride, Materials Science Forum, 941, 2203-2208, (2018). Abstract
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Abstract: Hydrogen storage is one of the most important industrial applications of titanium hydride (TiH2). A critical issue is the hydrogen release rate that strongly depends on the surface structure of TiH2 particles. This work reports the results of an experimental campaign carried out on TiH2 powders submitted to heat treatments in air at different temperatures and treatment times. After each heat treatment the TiH2 powders were examined by X-ray diffraction (XRD) and the results evidenced that the surface layer consists of TiO2 and Ti2O. Titanium oxide formation has been monitored by XRD at high temperature. Hydrogen release during heating of oxidized powders was investigated through temperature programmed desorption (TPD). Residual hydrogen in TiH2 depends on the specific treatment: higher temperature and soaking time of the treatment, lower its content.

Keywords: Hydrogen release | Oxidation heat treatments | Titanium hydride | X-ray diffraction

[44] Tedde G.M., Di Schino A., Donnini R., Montanari R., Richetta M., Santo L., Testani C., Varone A., An innovative industrial process for forging 7050 Al alloy, Materials Science Forum, 941, 1047-1052, (2018). Abstract
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Abstract: The effect of an unconventional thermal treatment method aimed to improve toughness behavior in Al alloys is reported. The method involves solution heat treating and an intermediate warm working step, before final ageing thermal treatment on a AA7050 high resistance aluminum alloy. Results show the possibility to increase fracture toughness behavior without tensile and conductivity (IACS) properties loss by adopting a warm deformation process instead of the standard cold deformation. Moreover, the adoption of an intermediate warm deformation instead of standard cold deformation, allows to reduce material microstructural grain-size heterogeneity.

Keywords: Al alloys | Mechanical properties | Warm working

[45] Antonelli L., Atzeni S., Batani D., Baton S.D., Brambrink E., Forestier-Colleoni P., Koenig M., Bel E.L., Maheut Y., Nguyen-Bui T., Richetta M., Rousseaux C., Ribeyre X., Schiavi A., Trela J., X-ray absorption radiography for high pressure shock wave studies, Journal of Instrumentation, 13(1), (2018). Abstract
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Abstract: The study of laser compressed matter, both warm dense matter (WDM) and hot dense matter (HDM), is relevant to several research areas, including materials science, astrophysics, inertial confinement fusion. X-ray absorption radiography is a unique tool to diagnose compressed WDM and HDM. The application of radiography to shock-wave studies is presented and discussed. In addition to the standard Abel inversion to recover a density map from a transmission map, a procedure has been developed to generate synthetic radiographs using density maps produced by the hydrodynamics code DUED. This procedure takes into account both source-target geometry and source size (which plays a non negligible role in the interpretation of the data), and allows to reproduce transmission data with a good degree of accuracy.

Keywords: X-ray radiography and digital radiography (DR) | X-ray transport and focusing

[46] Pizzoferrato R., Ciotta E., Ferrari I.V., Braglia M., Medaglia P.G., Mattoccia A., Di Giamberardino L., Richetta M., Knauth P., Di Vona M.L., Ionic conductivity of Zn–Al layered double hydroxide films grown on aluminum substrate, Solid State Ionics, 314, 30-35, (2018). Abstract
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Abstract: Zn–Al Layered Double Hydroxide (LDH) films were grown on aluminum substrates with different anions by a one-step, hydrothermal process at 80 °C, in which the metal substrate acts as both reactant and support. Since the films are made of partially-oriented nanoplatelets with controllable size and density, this approach can be a promising strategy for the fabrication of functionalized 3D electrodes and patterns on any surface. The presence of the different anions was confirmed by XPS measurements. Electrochemical Impedance Spectroscopy measurements were performed in order to study the electrical behavior of the films, with different inorganic anions intercalated in the LDH interlamellar space. The values of ionic conductivity are correlated to the anion type and the growth time of the films. F− intercalated LDHs present a higher conductivity than those with chloride and nitrate anions, which might be related to the lower hydration of the latter. Growth times around 8 h provided the best trade-off between shorter times, which affected the reproducibility of results, and longer periods, which induced formation of aggregates with a resulting lower conductivity.

Keywords: Hydrothermal synthesis | Ionic conductivity | LDH | Thin-films

[47] Ciotta E., Paoloni S., Richetta M., Prosposito P., Tagliatesta P., Lorecchio C., Venditti I., Fratoddi I., Casciardi S., Pizzoferrato R., Sensitivity to heavy-metal ions of unfolded fullerene quantum dots, Sensors (Switzerland), 17(11), (2017). Abstract
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Abstract: A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C60 buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions. The lattice structure of such unfolded fullerene quantum dots (UFQDs) is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu2+, Pb2+ and As(III) was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements and transmission electron microscope (TEM) images we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III) and the formation of precipitate with Pb2+ require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.

Keywords: Carbon materials | Heavy metals | Photoluminescence | Quenching | Sensors | Spectroscopy

[48] Montanari R., Pakhomova E., Pizzoferrato R., Richetta M., Varone A., Laser pulse effects on plasma-sprayed and bulk tungsten, Metals, 7(11), (2017). Abstract
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Abstract: Tungsten (W) is considered a promising plasma-facing material for protecting the divertor of the ITER (International Thermonuclear Experimental Reactor). The effects on W of transient thermal loads of high energy occurring in a tokamak under operative conditions have been simulated through a single laser pulse delivered by an Nd:YAG laser. Bulk and plasma-sprayed (PS) samples have been submitted to tests and successively examined via SEM (scanning electron microscopy) observations. In both types of materials, the laser pulse induces similar effects: (i) a crater forms in the spot central area; (ii) all around the area, the ejection and the movement of molten metal give rise to a ridge; (iii) in a more external area, the surface shows plates with jagged boundaries and cracks induced by thermal stresses; (iv) the pores present in the original material become preferred ablation sites. However, the affected surface area in PS samples is larger and asymmetric if compared to that of bulk material. Such a difference has been explained by considering how microstructural characteristics influence heat propagation from the irradiated spot, and it was found that grain size and shape play a decisive role.

Keywords: Laser | Microstructure | Nuclear fusion reactors | Plasma spraying | Tungsten

[49] Lovicu G., Fava A., Montanari R., Pizzoferrato R., Richetta M., Varone A., Testani C., ODS ferritic steel for nuclear reactors, Metallurgia Italiana, 109(10), 59-67, (2017). Abstract
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Abstract: Oxide dispersion strengthened steels are candidate materials for structural constituents in IV generation fission nuclear reactors and for fusion nuclear reactors. A reduced activation nano-oxide strengthened ferritic steel is produced by mechanical alloying with an average grain size of 400 nm. The steel is produced starting from nanometric powders of Fe-14Cr-1W-0.4Ti mixed with 0.3% Y2O3 powders, grinded by a low-energy mechanical alloying for 300 h and additionally consolidated by hot extrusion. Different heat treatments are carried out in temperature range from 1050 °C and 1150 °C. Transmission electron microscopy (TEM) analysis of hot extruded sample shows a equiaxed ferritic microstructure (Fig. 1a) with a high dislocation density (Fig. 1b) and a massive precipitation of different oxides particles (Fig. 2a) and complex non stoichiometric nano-oxide particles Y-Ti-O lesser than 10 nm (Fig. 2b). The precipitates distribution exhibits a remarkable stability in temperature and reduces the loss of mechanical characteristics even after extended exposure at 800 °C. After the heat treatments at 1050-1150 °C, the microstructure evolves towards a bimodal grain distribution as showed in Fig. 3. An inhomogeneous distribution of oxide particles inside the grains and different particles sizes after the heat treatment are showed respectively in Fig. 4 (a-b) and Fig.5 (a-b).

Keywords: Heat treatments | Low-energy mechanical alloying | Nanostructure, nano-oxides | Nuclear reactors | Ods steel

[50] De Sanctis M., Lovicu G., Buccioni M., Donato A., Richetta M., Varone A., Study of 13CR-4NI-(MO) (F6NM) steel grade heat treatment for maximum hardness control in industrial heats, Metals, 7(9), (2017). Abstract
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Abstract: The standard NACE MR0175 (ISO 15156) requires a maximum hardness value of 23 HRC for 13Cr-4Ni-(Mo) steel grade for sour service, requiring a double tempering heat treatment at temperature in the range 648–691°C for the first tempering and 593–621°C for the second tempering. Difficulties in limiting alloy hardness after the tempering of forged mechanical components (F6NM) are often faced. Variables affecting the thermal behavior of 13Cr-4Ni-(Mo) during single and double tempering treatments have been studied by means of transmission electron microscopy (TEM) observations, X-ray diffraction measurements, dilatometry, and thermo-mechanical simulations. It has been found that relatively low Ac1 temperatures in this alloy induce the formation of austenite phase above 600°C during tempering, and that the formed, reverted austenite tends to be unstable upon cooling, thus contributing to the increase of final hardness via transformation to virgin martensite. Therefore, it is necessary to increase the Ac1 temperature as much as possible to allow the tempering of martensite at the temperature range required by NACE without the detrimental formation of virgin martensite upon final cooling. Attempts to do so have been carried out by reducing both carbon (<0.02% C) and nitrogen (<100 ppm) levels. Results obtained herein show final hardness below NACE limits without an unacceptable loss of mechanical strength.

Keywords: Austenite reversion | Supermartensitic stainless steels | Tempering treatments

[51] Angella G., Barbieri G., Donnini R., Montanari R., Richetta M., Varone A., Electron beam welding of IN792 DS: Effects of pass speed and PWHT on microstructure and hardness, Materials, 10(9), (2017). Abstract
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Abstract: Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds (v) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests. In the as-welded condition; the structure of directionally oriented grains was completely lost in MZ. The γ' phase in MZ consisted of small (20-40 nm) round shaped particles and its total amount depended on both PHT and welding pass speed, whereas in HAZ, it was the same BM. Even if the amount of γ' phase in MZ was lower than that of the as-received material, the nanometric size of the particles induced an increase in hardness. EDS examinations did not show relevant composition changes in the γ' and phases. Post-welding heat treatments (PWHT) at 700 and 750 °C for two hours were performed on the best samples. After PWHTs, the amount of the ordered phase increased, and the effect was more pronounced at 750 °C, while the size of γ' particles in MZ remained almost the same. The hardness profiles measured across the joints showed an upward shift, but peak-valley height was a little lower, indicating more homogeneous features in the different zones.

Keywords: Electron beam welding | IN792 DS | Microstructure | Ni base superalloy | Post-welding heat treatments

[52] Fava A., Montanari R., Richetta M., Varone A., Analysis of relaxation processes in HNS due to interstitial-substitutional pairs, Metals, 7(7), (2017). Abstract
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Abstract: Mechanical Spectroscopy (MS) tests have been performed on a high nitrogen (0.8 wt %) austenitic steel (HNS) with resonance frequencies in the range of kHz. Two sets of samples have been examined: the first set in an as-prepared condition, the second one submitted to a heat treatment of 2 h at 800 °C, which induces a discontinuous precipitation of Cr2N phase. In both sets, the damping spectrum shows a broad peak whose position and shape is changed by the precipitation of Cr2N phase. The results are explained by considering interstitial-substitutional (i-s) interactions.

Keywords: Cr2N | Damping | Dynamic modulus | HNS | Interstitial-substitutional interactions | References

[53] Antonelli L., Atzeni S., Schiavi A., Baton S.D., Brambrink E., Koenig M., Rousseaux C., Richetta M., Batani D., Forestier-Colleoni P., Le Bel E., Maheut Y., Nguyen-Bui T., Ribeyre X., Trela J., Laser-driven shock waves studied by x-ray radiography, Physical Review E, 95(6), (2017). Abstract
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Abstract: Multimegabar laser-driven shock waves are unique tools for studying matter under extreme conditions. Accurate characterization of shocked matter is for instance necessary for measurements of equation of state data or opacities. This paper reports experiments performed at the LULI facility on the diagnosis of shock waves, using x-ray-absorption radiography. Radiographs are analyzed using standard Abel inversion. In addition, synthetic radiographs, which also take into account the finite size of the x-ray source, are generated using density maps produced by hydrodynamic simulations. Reported data refer to both plane cylindrical targets and hemispherical targets. Evolution and deformation of the shock front could be followed using hydrodynamic simulations.

[54] Angella G., Fava A., Montanari R., Richetta M., Varone A., Flat-top cylinder indenter examination of duplex stainless steel 2205 after different heat treatments, Metals, 7(5), (2017). Abstract
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Abstract: The duplex stainless steel 2205 was heat treated at 750◦C, 850◦C, and 900◦C for increasing durations of up to 10 h. The samples were investigated through light microscopy (LM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to characterize the volume fraction and morphology of the precipitated secondary phases. The samples were then tested via flat-top cylinder indenter for mechanical characterization (FIMEC) testing to determine the yield stresses that were found to be significantly affected by the different heat treatments. The yield stress evolution with heat treatments resulted in being correlated to both the relative volumes of the secondary phases and the morphology of the σ phase. The FIMEC test proved to be capable of detecting the effects of small amounts of secondary phases on yield stress in DSS 2205 and seems to be a promising technique for industrial applications.

Keywords: Duplex stainless steel 2205 | FIMEC indentation test | Heat treatments | Secondary intermetallic phases

[55] Zitelli C., Mengaroni S., Napoli G., Richetta M., Di Schino A., Metallurgical design of micro-alloyed high strength steels for forgings, Metallurgical Research and Technology, 114(6), (2017). Abstract
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Abstract: To fulfill the industrial demand of forged steels with high tensile properties and microstructural requirements coupled with reduced cost, the possibility to increase the properties of C-Mn steels by means of precipitation strengthening as achieved by micro-alloying (and without the addition of expensive elements such as Mo and Cr) has been evaluated. In order to do that, the effect of V addition has been exploited by means of metallurgical modelling followed by a laboratory ingot manufacturing. Heat treatment that has been designed aimed to achieve the target tensile properties. Results show that ASTM A694 F70 grade requirements can be fulfilled by 0.15% V addition and a proper heat treatment in a ferrite-pearlite microstructure, representative of a forged component.

Keywords: Micro-alloying | Steels | V

[56] Alunni A., Cianetti F., Di Schino A., Nobili F., Richetta M., Testani C., Effect of microstructural parameters on the fatigue behaviour of a AA2014-T6 alloy, Metallurgia Italiana, 109(5), 25-31, (2017). Abstract
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Abstract: The effect of two different cooling rates on the fatigue behaviour of a AA 2014 T6 alloy is reported in this paper. The study has been completed by a microstructural analysis carried out by means of scanning electron microscope, aimed to put in evidence the effect of microstructural evolution on the fatigue behaviour. A poor effect of the coooling rate on both microstructure and fatigue is found in the analysed cooling rate range.

Keywords: Al aloys | Fati gue | Microstructure

[57] De Sanctis M., Fava A., Lovicu G., Montanari R., Richetta M., Testani C., Varone A., Mechanical characterization of a nano-ODS steel prepared by low-energy mechanical alloying, Metals, 7(8), (2017). Abstract
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Abstract: An oxide dispersion strengthened (ODS) ferritic steel with nanometric grain size has been produced by low-energy mechanical alloying (MA) of steel powder (Fe-14Cr-1W-0.4Ti) mixed with Y2O3 particles (0.3 wt %) and successive hot extrusion (HE). The material exhibits superior mechanical properties with respect to the unreinforced steel up to 400 _C, then such differences tend to progressively decrease and at 700oC yield stress (YS) and ultimate tensile strength (UTS) values are very close. The microstructure and mechanical behaviour have been compared with those of ODS steels prepared by the most common process, high-energy MA, consolidation through hot isostatic pressing (HIP) or hot extrusion (HE), annealing around 1100oC for 1-2 h. The main strengthening mechanisms have been examined and discussed to explain the different behaviour. In addition, heat treatments in the range 1050-1150oC were carried out and a microstructural evolution with a relevant hardness decrease has been observed. TEM observations evidenced defect recovery and partial grain coarsening owing to the not perfectly homogeneous distribution of oxide particles.

Keywords: Heat treatments | Low-energy mechanical alloying | Mechanical properties | Nanostructure | ODS steel | Strengthening mechanisms

[58] Di Schino A., Richetta M., Evaluation of the metallurgical parameters effect on tensile properties in austenitic stainless steels, Acta Metallurgica Slovaca, 23(2), 111-121, (2017). Abstract
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Abstract: Even if relations predicting the mechanical properties on bars of austenitic stainless steels are already available, but no systematic works was carried out in order to predict mechanical properties in after cold rolling and annealing. The tensile properties of a large number of cold rolled and annealed AISI 304 stainless steel are here correlated with their chemical composition and microstructure. Quantitative effects of various strengthening mechanisms such as grain size, δ– ferrite content and solid solution strengthening by both interstitial and substitutional solutes are described. Interstitial solutes have by far the greatest strengthening effect and, among the substitutional solutes, the ferrite – stabilising elements have a greater effect than the austenite – stabilising elements. Regression equations are developed which predict with good accuracy the proof stress and tensile strength in AISI 304 stainless steels.

Keywords: Mechanical properties | Stainless steels

[59] Di Schino A., Richetta M., Effect of micro-alloying on quenching behaviour of steels for back-up rolls, Acta Metallurgica Slovaca, 23(2), 105-110, (2017). Abstract
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Abstract: The use of micro-alloyed steels for back-up rolls manufacturing gives the possibility to obtain advantages associated with the benefit of the application of micro-alloying elements and thermo-mechanical treatments. In this paper the effect of alloying elements has been evaluated aimed to improve steel hardenability and at the same time to reduce the fabrication cost. 3% Cr and 5% Cr steels are considered with a reduced Mo content. Analysis of alloying on hardenability is performed by means of metallurgical models and on laboratory scale. Results show a higher hardenability in the case of 5% Cr steels. Moreover, such family of steels also show a dependence on prior austenitic grain size. In both the steel families no warnings are detected in terms of residual austenite presence after quenching.

Keywords: Mechanical properties | Micro-alloyed steels | Quenching | Tempering

[60] di Nunzio P.E., Richetta M., di Schino A., Metallurgical design of boron microalloyed steels for forged components, Journal of Chemical Technology and Metallurgy, 52(4), 741-744, (2017). Abstract
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Abstract: To fulfill the industrial demand of forged steels with high mechanical and microstructural requirements coupled with reduced cost, the possibility to decrease the content of Mo and other alloying elements has been evaluated. The effect of boron addition (up to 30 ppm) on the steel hardenability has been investigated on two steels with different chemical composition at laboratory scale. In particular, the steel chemical composition has been designed in order to make effective the B addition in terms of hardenability. Two 80 kg ingots cast by a vacuum induction melting plant have been hot rolled by a pilot mill. The effect of B addition on hardenability has been evaluated and compared to that of steel for same application but without B. Results show an improvement of hardenability if 30 ppm B are added even if a Mo reduction is performed.

Keywords: Boron | Hardenability | Steel

[61] Gentili S., Richetta M., Mugnaini S., Mancini S., Staderini E.M., The use of vibrotactile stimulation for improving manual tasks in parkinson's disease patients, Materials Science Forum, 879, 2348-2351, (2017). Abstract
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Abstract: In spite of the potentially harmful effects of vibrations on the human body, a new path was recently opened for the use of these mechanical means in the therapeutic field. The stimulation of proprioceptive and exteroceptive sensitivity is the main target in both peripheral (diabetes type 1 and type 2) and central (stroke, Parkinson's disease multiple sclerosis) nervous system disorders, particularly for the recovery and maintenance of functional state. By the way the response to the treatment is highly variable from subject to subject. Our experimental apparatus consists of a virtual reality system "LEAP Motion" which involves the patient in the execution of visuo-manual tasks in a virtual environment while receiving vibrotactile stimulation. We also used a modular 36 channels EEG system and a vibratory stimulation system able of delivering vibratory stimuli perpendicular and tangential to the body surface area.The study evaluation of motor performance and the ability to perform the tasks of visuomotor task assigned, in the presence and absence of vibratory stimulation and in real time, evoked potentials in the cortex.The vibration frequency extended from 5 to 200 Hz and with accelerations between 0.3G and 1,5G with displacement amplitude of about 0.5 mm applied on the affected limb hand. As the frequency, the amplitude and the direction of the vibration may vary we studied the relationship between the characteristics of the stimulus and the perception in the cerebral cortex, or other levels of the nervous system, studying potential models of elicitation of the somatosensory system. In this regard, our study took into account patients with Parkinson's disease and in particular evoked potentials N18 N20 N24 N30 particularly related to tactile stimulus, and indicative of the level of perception and processing in the brain of the Parkinson's patient.

Keywords: EEG | Evoked potentials | Local vibration | Occupational medicine | Parkinson disease | Virtual reality

[62] Stollfuß C., Lietzau K.H., Richetta M., Foitzik A.H., Novel ESPI measurement prototype for analyzing biological samples from cell culture technique, Materials Science Forum, 879, 1859-1864, (2017). Abstract
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Abstract: An essential part of cell cultivation via cell culture technology is the determination and monitoring of culture parameters. Such parameters refer to the vitality or mutual mutations of the cell culture, while the actual number of living cells in each batch indicates the correct growth rate rather than stagnation or an overgrowth of the cell culture. Today such parameters are determined by applying light microscopy methods or by staining specific constituents of the cells. Commonly such methods are a stressful procedure for the studied cells. Most applied dyes are toxic over a certain period of time and thus they are used in low concentrations only when necessary. Within this work a new kind of measurement device prototype was designed to address these problems. This device is based on the Electronic Speckle Pattern Interferometry (ESPI). ESPI is an optical high-resolution method combined with a photonic analysis system capable of analyzing cellular deformations and oscillations. In this approach the combination of a greatly modified microscope together with ESPI method is presented. The apparatus allows the determination of cellular deformation (i) at very high magnifications, (ii) with high lateral resolution. Furthermore the system studies (iii) contact free, (iv) in vitro cells, in a non-invasive and non-destructive way. A co-developed cultivation system allows monitoring the culture parameters in real time minimizing the stress for the cell culture. Since no additional substances are needed, the presented prototype is automated to a large extent and can be operated by a special control- and regulation system (CRS) based on a microcontroller development board (Arduino Mega).

Keywords: Culture parameters | ESPI | Life Science | Non-destructive | Non-invasive | Stand-alone-System

[63] Malizia A., Gelfusa M., Murari A., Richetta M., Ciparisse J.F., Poggi L.A., Lungaroni M., Gaudio P., A novel facility to investigate dust mobilization in confined environments with applications to the security of the pharmaceutical industry, Materials Science Forum, 879, 1213-1219, (2017). Abstract
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Abstract: Many pharmaceutical industries all around the world are facing the problem of dust mobilization during the productive process of medicines. This mobilization can be dangerous for the safety of the operators working in the factory and for the safety of the factory itself. It is therefore necessary to develop predictive models to simulate and forecast dust mobilization. The Quantum Electronics and Plasma Physics (QEP) Research Group of the University of Rome Tor Vergata has developed a facility to experimentally replicate dust mobilization in different critical conditions in an enclosed environment. The measurements performed with diagnostics available in the facility, provide the boundary conditions to run numerical simulations and to validate mobilization models. Even if the initial field of application of this novel facility is dust mobilization is nuclear fusion, the methodology developed can be used for the medicine industry, for the agribusiness and others. The authors will present the experimental and numerical results discussing new applications.

Keywords: Dust | Experiments | Explosion | Medicine | Pharmaceutical industry | Simulation

[64] Lietzau K.H., Stollfuß C., Richetta M., Foitzik A.H., Experimental Bio-ESPI for validation of magnetic induced deformation on Hela cells, Materials Science Forum, 879, 1141-1146, (2017). Abstract
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Abstract: The determination of mechanical properties can provide insight into complex biochemical processes such as the cell cycle and even the progression of diseases. However, this field of biomechanical research strongly depends on a high-resolution measurement technology and a gentle stimulation method in order to examine these mostly biological samples in their original condition. In terms of this work, a different approach utilizing a modified ESPI setup and two types of ferrofluids is presented. By exposing the prepared specimen to an electro-magnetic field it has been possible to induce a local displacement and to monitor the deformation with the adapted ESPI setup.

Keywords: Detection of displacement | ESPI | Ferro fluids | HeLa | Nanoparticles

[65] Schneider S., Beyer H., Lange K., Bohmeyer W., Casalboni M., Richetta M., Foitzik A.H., Miniaturized laser power sensor via rapid phototyping, Materials Science Forum, 879, 1721-1724, (2017). Abstract
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Abstract: This work presents a photolithographic rapid prototyping process for producing thin films (“Rapid Phototyping”). This process allows a quick and cost-effective generation of scalable thermopile microstructures using commercial equipment and materials. Structural widths of 100x250μm can be produced reproducible in a lift-off process with an accuracy of 5 microns vertically and 30 microns horizontally.

Keywords: Bismuth | Foil | Laser | Lift Off | Optical power | Photolithography | Powersensor | Printer | PVD | Rapid phototyping | Rapid prototyping | Silver | Thermocouple | Thermopile | Thin film

[66] Richetta M., Gaudio P., Montanari R., Pakhomova E., Antonelli L., Laser pulse simulation of high energy transient thermal loads on bulk and plasma sprayed W for NFR, Materials Science Forum, 879, 1576-1581, (2017). Abstract
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Abstract: W is a plasma-facing material candidate for applications in future nuclear fusion reactors (NFR). In this work transient thermal loads of high energy have been simulated by interaction with a single laser pulse. The experiments have been carried out by using the Nd:Glass TVLPS laser working in first harmonic (wavelength λ = 1064 nm); the pulse parameters are: energy E ≈ 8 J, pulse duration Δt ≈ 15 ns, focal spot size Φ = 200 μm, surface power density on the focal plane I = 1.7 x 1012 W/cm2. The damage produced by the laser pulse on the surface of bulk and plasma sprayed W has been investigated by Scanning Electron Microscopy (SEM) observations. The preliminary results will bepresented.

Keywords: Bulk tungsten | Laser | Nuclear fusion reactors | Plasma sprayed tungsten | Simulation of plasma-tungsten interaction

[67] Costanza G., Montanari R., Richetta M., Tata M., Varone A., Evaluation of structural stability of materials through mechanical spectroscopy: Four case studies, Metals, 6(12), (2016). Abstract
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Abstract: Microstructural stability is one of the utmost important requirements for metallic materialsin engineering applications, particularly at high temperatures. The paper shows how Mechanical Spectroscopy (MS) (i.e., damping and dynamic modulus measurements) permits the monitoring of the evolution of lattice defects, porosity, and cracks which strongly affect the mechanical behavior of metals and sometimes lead to permanent damage. For this purpose, some applications of the technique to different metals and alloys (AISI 304 stainless steel, PWA 1483 single crystal superalloy, nanostructured FeMo prepared via SPS sintering and tungsten) of engineering interest are presented. These experiments have been carried out in lab conditions using bar-shaped samples at constant or increasing temperatures. The results can be used to orient the interpretation of frequency and damping changes observed through other instruments in components of complex shape during their in-service life.

Keywords: AISI 304 | Damping | Dynamic modulus | Mechanical spectroscopy | Microstructure stability | Nano-structured FeMo alloy | PWA 1483 | Tungsten

[68] Parracino S., Richetta M., Gelfusa M., Malizia A., Bellecci C., De Leo L., Perrimezzi C., Fin A., Forin M., Giappicucci F., Grion M., Marchese G., Gaudio P., Real-time vehicle emissions monitoring using a compact LiDAR system and conventional instruments: First results of an experimental campaign in a suburban area in southern Italy, Optical Engineering, 55(10), (2016). Abstract
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Abstract: Urban air pollution causes deleterious effects on human health and the environment. To meet stringent standards imposed by the European Commission, advanced measurement methods are required. Remote sensing techniques, such as light detection and ranging (LiDAR), can be a valuable option for evaluating particulate matter (PM), emitted by vehicles in urban traffic, with high sensitivity and in shorter time intervals. Since air quality problems persist not only in large urban areas, a measuring campaign was specifically performed in a suburban area of Crotone, Italy, using both a compact LiDAR system and conventional instruments for real-time vehicle emissions monitoring along a congested road. First results reported in this paper show a strong dependence between variations of LiDAR backscattering signals and traffic-related air pollution levels. Moreover, time-resolved LiDAR data averaged in limited regions, directly above conventional monitoring stations at the border of an intersection, were found to be linearly correlated to the PM concentration levels with a correlation coefficient between 0.75 and 0.84.

Keywords: air pollution | light detection and ranging | particulate matter | remote sensing | Urban | vehicle emissions

[69] Richetta M., Digiamberardino L., Mattoccia A., Medaglia P.G., Montanari R., Pizzoferrato R., Scarpellini D., Varone A., Kaciulis S., Mezzi A., Soltani P., Orsini A., Surface spectroscopy and structural analysis of nanostructured multifunctional (Zn, Al) layered double hydroxides, Surface and Interface Analysis, 48(7), 514-518, (2016). Abstract
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Abstract: Two types of (Zn, Al) layered double hydroxide were prepared by a hydrothermal process at room temperature using Zn salt precursors on Al foils. The examined LDHs differ for the hosted anions in the interlamellar space, namely Cl− and NO3−. Scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet photoemission spectroscopy have been used to characterize four types of the samples, representative of the two hosted anions (Cl− and NO3−) and two times of growth (6 and 24 h). X-ray photoelectron spectroscopy results permitted to describe the interactions between inorganic anions hosted in the interlamellar space and the metallic cations on the brucite layer. They also allowed giving a tentative explanation of the different morphologies observed by scanning electron microscopy. Copyright © 2016 The Authors Surface and Interface Analysis Published by John Wiley & Sons Ltd.

Keywords: Al | layered double hydroxide | UPS | XPS | Zn

[70] Antonelli L., Köster P., Folpini G., Maheut Y., Baffigi F., Cristoforetti G., Labate L., Levato T., Gizzi L.A., Consoli F., De Angelis R., Kalinowska Z., Chodukowski T., Rosinski M., Parys P., Pisarczyk T., Raczka P., Ryc L., Badziak J., Wolowski J., Smid M., Renner O., Krousky E., Pfeifer M., Skala J., Ullschmied J., Nicolaï P., Ribeyre X., Shurtz G., Atzeni S., Marocchino A., Schiavi A., Spindloe C., Dell T.O., Rhee Y.J., Richetta M., Batani D., Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition, Journal of Physics: Conference Series, 688(1), (2016). Abstract
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Abstract: We present experimental results at intensities relevant to Shock Ignition obtained at the sub-ns Prague Asterix Laser System in 2012. We studied shock waves produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at 1ω (1315 nm) at 7 x 1013 W/cm2 to create a pre-plasma on the front side of the target and a second at 3ω (438 nm) at ∼ 1016 W/cm2 to create the shock wave. Multilayer targets composed of 25 (or 40 m) of plastic (doped with Cl), 5 m of Cu (for K diagnostics) and 20 m of Al for shock measurement were used. We used X-ray spectroscopy of Cl to evaluate the plasma temperature, K imaging and spectroscopy to evaluate spatial and spectral properties of the fast electrons and a streak camera for shock breakout measurements. Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and Two Plasmon Decay) were studied by collecting the back scattered light and analysing its spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum pressure reached in our experiment we performed hydro simulations with CHIC and DUED codes. The maximum shock pressure generated in our experiment at the front side of the target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV.

[71] Camplani M., Malizia A., Gelfusa M., Barbato F., Antonelli L., Poggi L.A., Ciparisse J.F., Salgado L., Richetta M., Gaudio P., Image computing techniques to extrapolate data for dust tracking in case of an experimental accident simulation in a nuclear fusion plant, Review of Scientific Instruments, 87(1), (2016). Abstract
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Abstract: In this paper, a preliminary shadowgraph-based analysis of dust particles re-suspension due to loss of vacuum accident (LOVA) in ITER-like nuclear fusion reactors has been presented. Dust particles are produced through different mechanisms in nuclear fusion devices, one of the main issues is that dust particles are capable of being re-suspended in case of events such as LOVA. Shadowgraph is based on an expanded collimated beam of light emitted by a laser or a lamp that emits light transversely compared to the flow field direction. In the STARDUST facility, the dust moves in the flow, and it causes variations of refractive index that can be detected by using a CCD camera. The STARDUST fast camera setup allows to detect and to track dust particles moving in the vessel and then to obtain information about the velocity field of dust mobilized. In particular, the acquired images are processed such that per each frame the moving dust particles are detected by applying a background subtraction technique based on the mixture of Gaussian algorithm. The obtained foreground masks are eventually filtered with morphological operations. Finally, a multi-object tracking algorithm is used to track the detected particles along the experiment. For each particle, a Kalman filter-based tracker is applied; the particles dynamic is described by taking into account position, velocity, and acceleration as state variable. The results demonstrate that it is possible to obtain dust particles' velocity field during LOVA by automatically processing the data obtained with the shadowgraph approach.

[72] Gaudio P., Gelfusa M., Malizia A., Parracino S., Richetta M., De Leo L., Perrimezzi C., Bellecci C., Detection and monitoring of pollutant sources with Lidar/Dial techniques, Journal of Physics: Conference Series, 658(1), (2015). Abstract
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Abstract: It's well known that air pollution due to anthropogenic sources can have adverse effects on humans and the ecosystem. Therefore, in the last years, surveying large regions of the atmosphere in an automatic way has become a strategic objective of various public health organizations for early detection of pollutant sources in urban and industrial areas. The Lidar and Dial techniques have become well established laser based methods for the remote sensing of the atmosphere. They are often implemented to probe almost any level of the atmosphere and to acquire information to validate theoretical models about different topics of atmospheric physics. They can also be used for environment surveying by monitoring particles, aerosols and molecules. The aim of the present work is to demonstrate the potential of these methods to detect pollutants emitted from local sources (such as particulate and/or chemical compounds) and to evaluate their concentration. This is exemplified with the help of experimental data acquired in an industrial area in the south of Italy by mean of experimental campaign by use of pollutants simulated source. For this purpose, two mobile systems Lidar and Dial have been developed by the authors. In this paper there will be presented the operating principles of the system and the results of the experimental campaign.

Keywords: Dial | Lidar | pollutants | water vapour

[73] Lupelli I., Malizia A., Richetta M., Poggi L.A., Ciparisse J.F., Gelfusa M., Gaudio P., Simulations and Experiments to Reach Numerical Multiphase Informations for Security Analysis on Large Volume Vacuum Systems Like Tokamaks, Journal of Fusion Energy, 34(5), 959-978, (2015). Abstract
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Abstract: Dust re-suspension as a consequences of loss of vacuum accident (LOVA) or loss of coolant accident (LOCA) situations inside a nuclear fusion plant (ITER-like) is an important issue for the workers’ safety and for the security of the plant. The dust size expected inside tokamaks like ITER is of the order of microns (0.1–1000 μm). Analysis of the thermo fluid-dynamics and transport phenomena involved during an accidental pressurization transitory is necessary in order to set up and operated tokamaks with careful consideration of the potential risks. Computational fluid dynamics (CFD) study of LOVA scenario is a challenging task for today numerical methods and models because it involves 3D large vacuum volumes, multiphase flows ranging from highly supersonic to nearly incompressible and heat transfer simultaneously. Present work deals with development and experimental validation of CFD model, which simulates the complex thermo fluid-dynamic field and gives some indication about internal hazardous dust mobilization phenomena during vessel filling at near vacuum conditions, for supporting first instant of LOVA safety analysis. The research activity had been carried out in the framework of EURATOM–ENEA Association—University of Rome Tor Vergata Quantum Electronics Plasma Physics and Materials Research Group.

Keywords: CFD | Fusion | LOVA | Multiphase | Nuclear | Security

[74] Malizia A., Gelfusa M., Francia G., Boccitto M., Del Vecchio M., Di Giovanni D., Richetta M., Bellecci C., Gaudio P., Design of a new experimental facility to reproduce LOVA and LOCA consequences on dust resuspension, Fusion Engineering and Design, 98-99, 2191-2195, (2015). Abstract
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Abstract: Dust resuspension inside the vacuum vessel is one of the key security issues of the new-generation tokamaks (such as ITER or DEMO). It is well known that a fusion device generates dusts due to plasma-surface interactions, which cause a significant erosion of plasma facing components. Consequently, operators will have to manage several hundreds of kilograms of beryllium and tungsten dusts inside the VV. According to the reference categories, two main accidental situations lead to dusts re-suspension: loss of vacuum accidents (LOVA - air flow due to a rupture of a penetration line) and loss of coolant accidents (LOCA - fluid flashing due to a rupture of a coolant system pipe). The authors have gained a strong experience in the field of dust resuspension by virtue of the studies on the STARDUST facility, whose limitations, however, prevent from completing further analysis. These are, in particular, a reduced field of view to track the dust with optical techniques, the impossibility to replicate a LOVA from the upper port as well as any kind of LOCA. To overcome these problems, the authors have designed several new layouts of the facility. Numerical simulations to test the mechanical resistance together with a deep analysis of advantages and limitations have been performed for each layout. The authors will present the proposals for the new facility, the numerical results of the simulations and a comparison between the layouts analyzed. A new experimental facility will be then described to reproduce dust re-suspension due to both LOVA and LOCA consequences.

Keywords: ITER | LOCA | LOVA | Security

[75] Mattoccia A., Bernardone E., Digiamberardino L., Gaudio P., Malizia A., Orsini A., Pizzoferrato R., Richetta M., Scarpellini D., Medaglia P.G., Morphological and structural investigation of (Zn,Al) layered double hydroxides (LDH) nanoplatelets synthesized on aluminum-coated substrates, Metallurgia Italiana, 107(9), 15-22, (2015). Abstract
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Abstract: We have synthesized nanoplatelets of crystalline (Zn,Al) Layered Double Hydroxide (LDH) by a single-step and room temperature hydrothermal process on aluminum thin layers sputtered on different substrates. The structure, morphology, dimensions and compositions of nanoplatelets have been investigated by Scanning Electron Microscopy (SEM), X-Rays diffraction (XRD), Energy Dispersion Spectroscopy (EDS) and Photoluminescence (PL). Different behaviours of the thickness of nanoplatelets have been obtained by varying the most important growth parameters (thickness of Al coatings, growth temperature and duration). The thickness of the observed nanoplatelets results to be clearly dependent on the aluminun content available in the coating. On the contrary, the stoichiometry and the Zn/Al ratio does not change appreciably. Furthermore, for the thinnest aluminum layer, the LDH nanostructures result to be not well-shaped, and the excess zinc, on the one hand does not cause changes in the composition, on the other hand has as a consequence the formation of insulated ZnO nanorods. These samples show the defect-related visible luminescence, approximately centered at 600nm, and due to the nanorods presence, while no significant luminescence was expected from LDH nanosheets. Results obtained show that a controlled and spatially localized synthesis of Zn/Al LDH nanoplatelets can be obtained even on substrates having large surface area provided that the sputtered aluminum coating results to be thicker than 10nm, thus making possible the integration of these nanostructures on substrates of different nature.

Keywords: Hydrothermal growth | Layered double hydroxides | Materials characterization | Nanomaterials | Nanostructures on metallic coatings

[76] Barbato F., Ciambella L., Gaudio P., Montanari R., Richetta M., Antonelli L., Physical simulation of plasma-tungsten interaction in NFR, Metallurgia Italiana, 107(7-8), 17-23, (2015).
[77] Reale L., Bonfigli F., Lai A., Flora F., Albertano P., Di Giorgio M.L., Mezi L., Montereali R.M., Faenov A., Pikuz T., Almaviva S., Francucci M., Gaudio P., Martellucci S., Richetta M., Poma A., Contact X-ray microscopy of living cells by using LiF crystal as imaging detector, Journal of Microscopy, 258(2), 127-139, (2015). Abstract
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Abstract: In this paper, the use of lithium fluoride (LiF) as imaging radiation detector to analyse living cells by single-shot soft X-ray contact microscopy is presented. High resolved X-ray images on LiF of cyanobacterium Leptolyngbya VRUC135, two unicellular microalgae of the genus Chlamydomonas and mouse macrophage cells (line RAW 264.7) have been obtained utilizing X-ray radiation in the water window energy range from a laser plasma source. The used method is based on loading of the samples, the cell suspension, in a special holder where they are in close contact with a LiF crystal solid-state X-ray imaging detector. After exposure and sample removal, the images stored in LiF by the soft X-ray contact microscopy technique are read by an optical microscope in fluorescence mode. The clear image of the mucilaginous sheath the structure of the filamentous Leptolyngbya and the visible nucleolus in the macrophage cells image, are noteworthiness results. The peculiarities of the used X-ray radiation and of the LiF imaging detector allow obtaining images in absorption contrast revealing the internal structures of the investigated samples at high spatial resolution. Moreover, the wide dynamic range of the LiF imaging detector contributes to obtain high-quality images. In particular, we demonstrate that this peculiar characteristic of LiF detector allows enhancing the contrast and reveal details even when they were obscured by a nonuniform stray light.

Keywords: Algae | Chlamydomonas | Contact X-ray microscopy | Leptolyngbya | Lithium fluoride detectors | Macrophage RAW 264.7

[78] Barbato F., Scarpellini D., Malizia A., Gaudio P., Richetta M., Antonelli L., X-ray high-resolution spectroscopy for laser-produced plasma, Physics Procedia, 62, 84-91, (2015). Abstract
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Abstract: The study of the emission spectrum gives information about the material generating the spectrum itself and the condition in which this is generated. The wavelength spectra lines are linked to the specific element and plasma conditions (electron temperature, density), while their shape is influenced by several physical effects like Stark and Doppler ones. In this work we study the X-ray emission spectra of a copper laser-produced plasma by using a spherical bent crystal spectrometer to measure the electron temperature. The facility used is the laser TVLPS, at the Tor Vergata University in Rome. It consists of a Nd:Glass source (in first harmonic - 1064 nm) whose pulse parameters are: 8 J in energy, time duration of 15 ns and a focal spot diameter of 200 μm. The adopted spectrometer is based on a spherical bent crystal of muscovite. The device combines the focusing property of a spherical mirror with the Bragg's law. This allows to obtain a great power resolution but a limited range of analysis. In our case the resolution is on average 80 eV. As it is well-known, the position of the detector on the Rowland's circle is linked to the specific spectral range which has been studied. To select the area to be investigated, we acquired spectra by means of a flat spectrometer. The selected area is centered on 8.88 Å. To calibrate the spectrum we wrote a ray-tracing MATLAB code, which calculates the detector alignment parameters and calibration curve. We used the method of line ratio to measure the electron temperature. This is possible because we assumed the plasma to be in LTE condition. The temperature value was obtained comparing the experimental one, given by the line ratio, with the theoretical one, preceded by FLYCHK simulations.

Keywords: Laser-plasma | Spherical bent crystal | X-ray spectroscopy

[79] Gaudio P., Malizia A., Camplani M., Barbato F., Antonelli L., Gelfusa M., Del Vecchio M., Salgado L., Bellecci C., Richetta M., Shadowgraph technique applied to STARDUST facility for dust tracking: First results, Physics Procedia, 62, 97-101, (2015). Abstract
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Abstract: The problem of dust resuspension in case of Loss Of Vacuum Accident (LOVA) in a nuclear fusion plant (ITER or DEMO like) is an important issue for the safety of workers and the security of environment. The Quantum Electronics and Plasma Physics Research Group has implemented an optical set-up to track dust during a LOVA reproduction inside the experimental facility STARDUST. The shadowgraph technique, in this work, it is applied to track dark dust (like Tungsten). The shadowgraph technique is based on an expanded collimated beam of light emitted by a laser (or a lamp) transversely to the flow field direction. Inside STARDUST the dust moving in the air flow causes variations of refractive index of light that can be detected by the means of a CCD camera. A spatial modulation of the light-intensity distribution on the camera can be measured. The resulting pattern is a shadow of the refractive index field that prevails in the region of the disturbance. The authors use an incandescent white lamp to illuminate the vacuum vessel of STARDUST facility. The light-area passes through the test section that has to be investigated and the images of the dust shadows are collected with a fast CCD camera. The images are then elaborated with mathematical algorithms to obtain information about the velocity fields of dust during the accidents reproduction. The experimental set-up together with a critical analysis of the first results are presented in this paper.

Keywords: Computer vision | Dust | ITER. | Nuclear fusion plants | Radioactive | Safety | Security | Shadowgraph | Tracking

[80] Scarpellini D., Falconi C., Gaudio P., Mattoccia A., Medaglia P.G., Orsini A., Pizzoferrato R., Richetta M., Morphology of Zn/Al layered double hydroxide nanosheets grown onto aluminum thin films, Microelectronic Engineering, 126, 129-133, (2014). Abstract
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Abstract: Layered double hydroxide (LDH) nanosheets have been fabricated by a one-step, room-temperature, hydrothermal process on sputtered-aluminum thin substrates, in which the metal substrate acts as both reactant and support. The morphology, dimensions and composition of the obtained nanostructures have been characterized as a function of the substrate thickness by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion spectroscopy (EDS) and photoluminescence measurements. While the lateral size of the observed LDH nanosheets depends on the available aluminum, the stoichiometry does not change appreciably. Even for the lowest values of the aluminum thickness, the excess zinc does not alter the chemical composition of LDH, but rather produces ZnO nanorods that show the characteristic defect-related broad visible photoluminescence centered at approximately 600 nm. The results show that a controlled growth of Zn/Al LDH nanosheets can be achieved onto sputtered aluminum thin layers with thicknesses as low as 10 nm, which can be important for the integration of LDH on generic substrates.n © 2014 Elsevier Ltd. All rights reserved.

Keywords: Hydrothermal technique | Layered double hydroxide | Nanoplatelets | Nanostructures | Photoluminescence

[81] Malizia A., Camplani M., Gelfusa M., Antonelli L., Barbato F., Del Vecchio M., Richetta M., Salgado L., Bellecci C., Gaudio P., Optical techniques to study the dust resuspension problem in case of LOVA: Comparison of results obtained with PIV and Shadowgraph, 41st EPS Conference on Plasma Physics, EPS 2014, 2014-Jun, (2014).
[82] Gaudio P., Gelfusa M., Malizia A., Parracino S., Richetta M., Murari A., Vega J., Automatic localization of backscattering events due to particulate in urban areas, Proceedings of SPIE - The International Society for Optical Engineering, 9244, (2014). Abstract
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Abstract: Particulate matter (PM), emitted by vehicles in urban traffic, can greatly affect environment air quality and have direct implications on both human health and infrastructure integrity. The consequences for society are relevant and can impact also on national health. Limits and thresholds of pollutants emitted by vehicles are typically regulated by government agencies. In the last few years, the interest in PM emissions has grown substantially due to both air quality issues and global warming. Lidar-Dial techniques are widely recognized as a costeffectivealternative to monitor large regions of the atmosphere. To maximize the effectiveness of the measurements and to guarantee reliable, automatic monitoring of large areas, new data analysis techniques are required. In this paper, an original tool, the Universal Multi-Event Locator (UMEL), is applied to the problem of automatically indentifying the time location of peaks in Lidar measurements for the detection of particulate matter emitted by anthropogenic sources like vehicles. The method developed is based on Support Vector Regression and presents various advantages with respect to more traditional techniques. In particular, UMEL is based on the morphological properties of the signals and therefore the method is insensitive to the details of the noise present in the detection system. The approach is also fully general, purely software and can therefore be applied to a large variety of problems without any additional cost. The potential of the proposed technique is exemplified with the help of data acquired during an experimental campaign in the field in Rome.

Keywords: Lidar | Particulate | Support Vector Regression | UMEL

[83] Lupelli I., Gaudio P., Gelfusa M., Malizia A., Belluzzo I., Richetta M., Numerical study of air jet flow field during a loss of vacuum, Fusion Engineering and Design, 89(9-10), 2048-2052, (2014). Abstract
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Abstract: Air leakage into tokamaks vacuum vessel during plasma burning or maintenance operations may lead to the fast pressurization of the vacuum vessel. A fraction of the dust inventory present in the vacuum vessel can be mobilized threatening the safety of staff and workers on site, the local population and the environment. A numerical analysis of the physical phenomena involved in such accidents is necessary in order to predict the thermal-fluid dynamics into the vacuum vessel after air ingress and consequent dust mobilization. Accuracy of the numerical results is also required in order to provide a sufficient margin in the design of the safety systems. The numerical simulation of Loss of Vacuum Accident (LOVA) scenarios is a challenging task for today numerical methods and models because it involves large volumes, multiphase flows ranging from highly supersonic to nearly incompressible and contemporary heat transfer. The drag force exerted on the dust by a moving fluid due to the viscous surface shear stress and pressure distribution around the dust particles depends mainly on the Reynolds number, i.e. property of the fluid (kinematic viscosity), its mean velocity and characteristic length of the geometry. For a fixed geometry, the key parameter for the dust mobilization is the velocity field of the continuous phase, and its thermodynamics properties, inside the vacuum vessel. In this contribution, the authors present and discuss the results of numerical simulations of air jet flow field during a LOVA with particular attention to the comparison with the experimental data and differences arising from the use of different types of grid resolution and turbulence models (Zero-Equation, k-ω and SST). © 2014 Elsevier B.V.

Keywords: CFD | LOVA | Safety

[84] Malizia A., Camplani M., Gelfusa M., Lupelli I., Richetta M., Antonelli L., Conetta F., Scarpellini D., Carestia M., Peluso E., Bellecci C., Salgado L., Gaudio P., Dust tracking techniques applied to the STARDUST facility: First results, Fusion Engineering and Design, 89(9-10), 2098-2102, (2014). Abstract
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Abstract: An important issue related to future nuclear fusion reactors fueled with deuterium and tritium is the creation of large amounts of dust due to several mechanisms (disruptions, ELMs and VDEs). The dust size expected in nuclear fusion experiments (such as ITER) is in the order of microns (between 0.1 and 1000 μm). Almost the total amount of this dust remains in the vacuum vessel (VV). This radiological dust can re-suspend in case of LOVA (loss of vacuum accident) and these phenomena can cause explosions and serious damages to the health of the operators and to the integrity of the device. The authors have developed a facility, STARDUST, in order to reproduce the thermo fluid-dynamic conditions comparable to those expected inside the VV of the next generation of experiments such as ITER in case of LOVA. The dust used inside the STARDUST facility presents particle sizes and physical characteristics comparable with those that created inside the VV of nuclear fusion experiments. In this facility an experimental campaign has been conducted with the purpose of tracking the dust re-suspended at low pressurization rates (comparable to those expected in case of LOVA in ITER and suggested by the General Safety and Security Report ITER-GSSR) using a fast camera with a frame rate from 1000 to 10,000 images per second. The velocity fields of the mobilized dust are derived from the imaging of a two-dimensional slice of the flow illuminated by optically adapted laser beam. The aim of this work is to demonstrate the possibility of dust tracking by means of image processing with the objective of determining the velocity field values of dust re-suspended during a LOVA. © 2014 Elsevier B.V.

Keywords: Computer vision | Dust tracking | Nuclear fusion plants | Particle image velocimetry (PIV) | Safety | Security

[85] Gelfusa M., Malizia A., Parracino S., Richetta M., Bellecci C., Avolio E., De Leo L., Perrimezzi C., Gaudio P., Detection of pollutant sources in the atmosphere with Lidar/Dial techniques: Results of an experimental campaign in the south of Italy, 2014 Fotonica AEIT Italian Conference on Photonics Technologies, Fotonica AEIT 2014, (2014). Abstract
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Abstract: In the last years, surveying large regions of the atmosphere in an automatic way, for early detection of pollutant sources in urban and industrial areas, has become a strategic objective of various public health organizations. The Lidar/Dial technique has become a well-established laser remote sensing method for atmosphere monitoring. It is often used to probe almost any level of the atmosphere and to acquire information necessary to validate theoretical models about different topics of atmospheric physics. It can also be deployed for environment surveying by monitoring particles, aerosols and molecules. For these reasons, an experimental campaign for evaluating the performances of a Lidar/Dial system in detecting pollutants (particulate and/or chemical compounds) has been carried out in an industrial area in the south of Italy. In this work, a homemade Lidar/Dial system (developed and built by the authors) and the results of the experimental campaign will be presented and discussed. © 2014 AEIT.

Keywords: Dial | Lidar | Pollutants | Water vapour

[86] Gelfusa M., Gaudio P., Malizia A., Murari A., Vega J., Richetta M., Gonzalez S., UMEL: A new regression tool to identify measurement peaks in LIDAR/DIAL systems for environmental physics applications, Review of Scientific Instruments, 85(6), (2014). Abstract
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Abstract: Recently, surveying large areas in an automatic way, for early detection of both harmful chemical agents and forest fires, has become a strategic objective of defence and public health organisations. The Lidar and Dial techniques are widely recognized as a cost-effective alternative to monitor large portions of the atmosphere. To maximize the effectiveness of the measurements and to guarantee reliable monitoring of large areas, new data analysis techniques are required. In this paper, an original tool, the Universal Multi Event Locator, is applied to the problem of automatically identifying the time location of peaks in Lidar and Dial measurements for environmental physics applications. This analysis technique improves various aspects of the measurements, ranging from the resilience to drift in the laser sources to the increase of the system sensitivity. The method is also fully general, purely software, and can therefore be applied to a large variety of problems without any additional cost. The potential of the proposed technique is exemplified with the help of data of various instruments acquired during several experimental campaigns in the field. © 2014 AIP Publishing LLC.

[87] Malizia A., Lupelli I., Richetta M., Gelfusa M., Bellecci C., Gaudio P., Safety analysis in large volume vacuum systems like tokamak: Experiments and numerical simulation to analyze vacuum ruptures consequences, Advances in Materials Science and Engineering, 2014, (2014). Abstract
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Abstract: The large volume vacuum systems are used in many industrial operations and research laboratories. Accidents in these systems should have a relevant economical and safety impact. A loss of vacuum accident (LOVA) due to a failure of the main vacuum vessel can result in a fast pressurization of the vessel and consequent mobilization dispersion of hazardous internal material through the braches. It is clear that the influence of flow fields, consequence of accidents like LOVA, on dust resuspension is a key safety issue. In order to develop this analysis an experimental facility is been developed: STARDUST. This last facility has been used to improve the knowledge about LOVA to replicate a condition more similar to appropriate operative condition like to kamaks. By the experimental data the boundary conditions have been extrapolated to give the proper input for the 2D thermofluid-dynamics numerical simulations, developed by the commercial CFD numerical code. The benchmark of numerical simulation results with the experimental ones has been used to validate and tune the 2D thermofluid-dynamics numerical model that has been developed by the authors to replicate the LOVA conditions inside STARDUST. In present work, the facility, materials, numerical model, and relevant results will be presented. © 2014 A. Malizia et al.

[88] Maheut Y., Antonelli L., Atzeni S., Badziak J., Baffigi F., Batani D., Cecchetti C., Chodukowski T., Consoli F., Cristoforetti G., De Angelis R., Folpini G., Gizzi L.A., Kalinowska Z., Kucharik M., Köster P., Krousky E., Labate L., Levato T., Liska R., Malka G., Marocchino A., Nicolaï P., O'Dell T., Parys P., Pisarczyk T., Ra̧czka P., Renner O., Rhee Y.J., Ribeyre X., Richetta M., Rosinski M., Ryć L., Skala J., Schiavi A., Schurtz G., Smid M., Spindloe C., Ullschmied J., Wolowski J., Zaraś A., Experiment on laser interaction with a planar target for conditions relevant to shock ignition, Physica Scripta, T161, (2014). Abstract
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Abstract: We report the experiment conducted on the Prague Asterix Laser System (PALS) laser facility dedicated to make a parametric study of the laser-plasma interaction under the physical conditions corresponding to shock ignition thermonuclear fusion reactions. Two laser beams have been used: the auxiliary beam, for preplasma creation on the surface of a plastic foil, and the main beam to launch a strong shock. The ablation pressure is inferred from the volume of the crater in the Cu layer situated behind the plastic foil and by shock breakout chronometry. The population of fast electrons is analyzed by Kα emission spectroscopy and imaging. The preplasma is characterized by three-frame interferometry, x-ray spectroscopy and ion diagnostics. The numerical simulations constrained with the measured data gave a maximum pressure in the plastic layer of about 90 Mbar. © 2014 The Royal Swedish Academy of Sciences.

Keywords: hot electron | laser | plasma | shock | shock ignition

[89] Batani D., Antonelli L., Atzeni S., Badziak J., Baffigi F., Chodukowski T., Consoli F., Cristoforetti G., De Angelis R., Dudzak R., Folpini G., Giuffrida L., Gizzi L.A., Kalinowska Z., Koester P., Krousky E., Krus M., Labate L., Levato T., Maheut Y., Malka G., Margarone D., Marocchino A., Nejdl J., Nicolai P., O'Dell T., Pisarczyk T., Renner O., Rhee Y.J., Ribeyre X., Richetta M., Rosinski M., Sawicka M., Schiavi A., Skala J., Smid M., Spindloe C., Ullschmied J., Velyhan A., Vinci T., Generation of high pressure shocks relevant to the shock-ignition intensity regime, Physics of Plasmas, 21(3), (2014). Abstract
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Abstract: An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤1016 W/cm2, relevant for the "shock ignition" approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region. © 2014 AIP Publishing LLC.

[90] Gaudio P., Gelfusa M., Malizia A., Richetta M., Antonucci A., Ventura P., Murari A., Vega J., Design and development of a compact Lidar/Dial system for aerial surveillance of urban areas, Proceedings of SPIE - The International Society for Optical Engineering, 8894, (2013). Abstract
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Abstract: Recently surveying large areas in an automatic way, for early detection of harmful chemical agents, has become a strategic objective of defence and public health organisations. The Lidar-Dial techniques are widely recognized as a cost-effective alternative to monitor large portions of the atmosphere but, up to now, they have been mainly deployed as ground based stations. The design reported in this paper concerns the development of a Lidar-Dial system compact enough to be carried by a small airplane and capable of detecting sudden releases in air of harmful and/or polluting substances. The proposed approach consists of continuous monitoring of the area under surveillance with a Lidar type measurement. Once a significant increase in the density of backscattering substances is revealed, it is intended to switch to the Dial technique to identify the released chemicals and to determine its concentration. In this paper, the design of the proposed system is described and the simulations carried out to determine its performances are reported. For the Lidar measurements, commercially available Nd- YAG laser sources have already been tested and their performances, in combination with avalanche photodiodes, have been experimentally verified to meet the required specifications. With regard to the DIAL measurements, new compact CO2 laser sources are being investigated. The most promising candidate presents an energy per pulse of about 50 mJ typical, sufficient for a range of at least 500m. The laser also provides the so called «agile tuning» option that allows to quickly tune the wavelength. To guarantee continuous, automatic surveying of large areas, innovative solutions are required for the data acquisition, self monitoring of the system and data analysis. The results of the design, the simulations and some preliminary tests illustrate the potential of the chosen, integrated approach. © 2013 SPIE.

Keywords: Aerial surveillance | Dial | Lidar | Monitoring system | Pollutants | UMEL

[91] Koester P., Antonelli L., Atzeni S., Badziak J., Baffigi F., Batani D., Cecchetti C.A., Chodukowski T., Consoli F., Cristoforetti G., Angelis R.D., Folpini G., Gizzi L.A., Kalinowska Z., Krousky E., Kucharik M., Labate L., Levato T., Liska R., Malka G., Maheut Y., Marocchino A., Nicolai P., O'Dell T., Parys P., Pisarczyk T., Raczka P., Renner O., Rhee Y.J., Ribeyre X., Richetta M., Rosinski M., Ryc L., Skala J., Schiavi A., Schurtz G., Smid M., Spindloe C., Ullschmied J., Wolowski J., Zaras A., Recent results from experimental studies on laser-plasma coupling in a shock ignition relevant regime, Plasma Physics and Controlled Fusion, 55(12), (2013). Abstract
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Abstract: Shock ignition (SI) is an appealing approach in the inertial confinement scenario for the ignition and burn of a pre-compressed fusion pellet. In this scheme, a strong converging shock is launched by laser irradiation at an intensity Iλ2 > 1015 W cm-2 μm2 at the end of the compression phase. In this intensity regime, laser-plasma interactions are characterized by the onset of a variety of instabilities, including stimulated Raman scattering, Brillouin scattering and the two plasmon decay, accompanied by the generation of a population of fast electrons. The effect of the fast electrons on the efficiency of the shock wave production is investigated in a series of dedicated experiments at the Prague Asterix Laser Facility (PALS). We study the laser-plasma coupling in a SI relevant regime in a planar geometry by creating an extended preformed plasma with a laser beam at ∼7 × 1013 W cm-2 (250 ps, 1315 nm). A strong shock is launched by irradiation with a second laser beam at intensities in the range 1015-1016 W cm-2 (250 ps, 438 nm) at various delays with respect to the first beam. The pre-plasma is characterized using x-ray spectroscopy, ion diagnostics and interferometry. Spectroscopy and calorimetry of the backscattered radiation is performed in the spectral range 250-850 nm, including (3/2)ω, ω and ω/2 emission. The fast electron production is characterized through spectroscopy and imaging of the Kα emission. Information on the shock pressure is obtained using shock breakout chronometry and measurements of the craters produced by the shock in a massive target. Preliminary results show that the backscattered energy is in the range 3-15%, mainly due to backscattered light at the laser wavelength (438 nm), which increases with increasing the delay between the two laser beams. The values of the peak shock pressures inferred from the shock breakout times are lower than expected from 2D numerical simulations. The same simulations reveal that the 2D effects play a major role in these experiments, with the laser spot size comparable with the distance between critical and ablation layers. © 2013 IOP Publishing Ltd.

[92] Benedetti M., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Richetta M., Large eddy simulation of Loss of Vacuum Accident in STARDUST facility, Fusion Engineering and Design, 88(9-10), 2665-2668, (2013). Abstract
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Abstract: The development of computational fluid dynamic (CFD) models of air ingress into the vacuum vessel (VV) represents an important issue concerning the safety analysis of nuclear fusion devices, in particular in the field of dust mobilization. The present work deals with the large eddy simulations (LES) of fluid dynamic fields during a vessel filling at near vacuum conditions to support the safety study of Loss of Vacuum Accidents (LOVA) events triggered by air income. The model's results are compared to the experimental data provided by STARDUST facility at different pressurization rates (100 Pa/s, 300 Pa/s and 500 Pa/s). Simulation's results compare favorably with experimental data, demonstrating the possibility of implementing LES in large vacuum systems as tokamaks. © 2013 Elsevier B.V.

Keywords: Dust mobilization | Experiments | LES | Loss of Vacuum Accident | Nuclear fusion safety | Numerical simulation

[93] Gaudio P., Gelfusa M., Malizia A., Richetta M., Serafini C., Ventura P., Bellecci C., De Leo L., Lo Feudo T., Murari A., New frontiers of forest fire protection: A portable laser system (FfED), WSEAS Transactions on Environment and Development, 9(3), 195-205, (2013). Abstract
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Abstract: Forest fires are one of the worst events that can cause environmental and economic damage. It is impossible to predict the moment in which these events can happen because they can be the consequence of particular environmental conditions or of a voluntary criminal act. As a consequence it is necessary to work on a solution that allows surveying automatically the territory. The portable LIDAR system that the Quantum Electronics and Plasma Physics group has developed in collaboration with CRATI s.c.r.l. deals with these needs. The system, called FfED (Forest fire Early Detection system,) is presented in this paper together with the numerical and experimental results (in cell and in field), a discussion about their comparison and the possible future improvements. © 2013 - All Rights Reserved.

Keywords: COMSOL Multhiphysics | Early Detection | Environment | Forest Fires | LIDAR | Numerical simulation | Portable system

[94] Gallo R., De Angelis P., Malizia A., Conetta F., Di Giovanni D., Antonelli L., Gallo N., Fiduccia A., D'Amico F., Fiorito R., Richetta M., Bellecci C., Gaudio P., Development of a georeferencing software for radiological diffusion in order to improve the safety and security of first responders, Defence S and T Technical Bulletin, 6(1), 21-32, (2013). Abstract
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Abstract: This study deals with the need to develop analytical instruments to optimise rescue operations involving radiological exposure. It reports several aspects of analysis and characterisation of orphan radioactive sources. The protection problems in cases of detection and securing of radioactive sources are analysed, with particular attention to safety and security of operators and population from exposure, identification of attention areas, and detection of specific values of dose. After defining the characteristics of orphan radioactive sources, the authors examine the fundamental radiometric parameters. All these parameters have been integrated in a customised software, known as GREAT (Georeferenced Radiological Evaluation & Analysis Tool), that allows for rapid mapping of radiological risks by georeferencing of the data collected. Particular attention has been dedicated to the theoretical model and support tools aided to the choices of first responders. Radiological event, their consequences and the tools developed will be described by the authors in order to demonstrate the importance of this software for improvement of rescue operations.

Keywords: First responders | Georeferencing software | Orphan radioactive source | Radiation dose | Radiological diffusion

[95] Cenciarelli O., Malizia A., Marinelli M., Pietropaoli S., Gallo R., D'Amico F., Bellecci C., Fiorito R., Gucciardino A., Richetta M., Gaudio P., Evaluation of biohazard management of the Italian national fire brigade, Defence S and T Technical Bulletin, 6(1), 33-41, (2013). Abstract
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Abstract: Biohazards are non-conventional threats that are very difficult to manage. This is due to difficulties in the identification of biological agents that are responsible for the onset of a disease, which can be bacteria, viruses, fungus or toxins. In Italy, the first response system to biohazards is provided by the National Fire Brigade (NFB) (Corpo Nazionale dei Vigili del Fuoco - CNVVF). The aim of this work is to evaluate the procedures adopted by the NFB for the management of biohazards. This is done by comparing the statistics of NFB interventions in 2000-2010 for potential biohazard events, and chemical and radioactive risks. A series of solutions is then proposed to improve the NFB's national response system for biohazards.

Keywords: Biohazards | Biological | Chemical | Interventions | National fire brigade (NFB) | Radiological and nuclear (CBRN) | Specialist biologists

[96] Levato T., Calvetti M., Anelli F., Batani D., Benocci R., Cacciotti L., Cecchetti C.A., Cerafogli O., Chimenti P., Clozza A., Drenska N., Esposito A., Faccini R., Fioravanti S., Gamucci A., Gatti C., Giulietti A., Giulietti D., Labate L., Lollo V., Martellotti S., Monteduro M., Pace E., Pathak N.C., Pellegrino L., Piastra F., Pistoni M., Di Pirro G., Di Raddo R., Rotundo U., Ricci R., Richetta M., Vaccarezza C., Valente P., Gizzi L.A., First electrons from the new 220 TW Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME) at Frascati National Laboratories (LNF), Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 720, 95-99, (2013). Abstract
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Abstract: A new era of laser based plasma accelerators is emerging following the commissioning of many high power laser facilities around the world. Extremely short (tens of fs) laser pulses with energy of multi-joules level are available at these newly built facilities. Here we describe the new 220 TW FLAME facility. In particular we discuss the laser system general layout, the main measurements on the laser pulse parameters, the underground target area. Finally we give an overview of the first results of the Self-Injection Test Experiment (SITE), obtained at a low laser energy. This initial low laser energy experimental campaign was necessary for the validation of the radio-protection shielding (Esposito, 2011 [1]) we discuss here. With respect to our preliminary configuration, with a pulse duration of 30 fs and a focusing optic of F/15, we discuss here the minimum laser energy requirements for electron acceleration and the forward transmitted optical radiation. © 2012 Elsevier B.V.

Keywords: Laser plasma acceleration | Radio-protection

[97] Badziak J., Chodukowski T., Kalinowska Z., Parys P., Pisarczyk T., Ra̧czka P., Rosiński M., Ryć L., Woowski J., Zaraś A., Gizzi L.A., Baffigi F., Cristoforetti G., Koester P., Labate L., Antonelli L., Richetta M., Batani D., Folpini G., Malka G., Maheut Y., Krousky E., Pfeifer M., Renner O., Smid M., Skala J., Ullschmied J., Kucharik M., Liska R., Rhee Y.J., Consoli F., De Angelis R., Spindloe C., The influence of preformed plasma on a laser-driven shock produced in a planar target at the conditions relevant to shock ignition, 40th EPS Conference on Plasma Physics, EPS 2013, 2, 842-845, (2013). Abstract
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Abstract: The effect of preformed plasma on a laser-driven shock produced in a planar target at the conditions relevant to the shock ignition scenario of ICF was investigated at the kilojoule PALS laser facility. Characteristics of the preformed plasma were controlled by the delay Δt between the auxiliary beam (1ω, 7×1013 W/cm2) and the main 3ω, 250 ps laser pulse of intensity up to 1016 W/cm2, and measured with the use of 3-frame interferometry, ion diagnostics, an X-ray spectrometer and Kα imaging. Parameters of the shock produced in a CH(Cl) target (25 μm or 40 μm thick) by the intense 3ω laser pulse with energy ranging between 50 J and 200 J were determined by measuring the craters produced by the shock in a massive Cu target behind the layer of plastic. The volume and the shape of these craters was found to depend rather weakly on the preplasma thickness, which implies the same is true for the total energy of shocks and pressure generated by them. From the comparison of the measured crater parameters with those obtained in 2D simulations using the PALE code, it was estimated that for I3ω 1016 W/cm2 the pressure at the rear (non-irradiated) side of the 25-μm plastic layer reaches about 100 Mbar. Copyright © (2013) by the European Physical Society (EPS).

[98] Levato T., Cecchetti C.A., Labate L., Gizzi L.A., Drenska N., Faccini R., Martellotti S., Tani F., Gatti C., Vaccarezza C., Valente P., Giulietti A., Lollo V., Giulietti D., Pathak N.C., Piastra F., Richetta M., Preliminary results of the self-injection test experiment (SITE) at FLAME, Proceedings of the International School of Physics "Enrico Fermi", 179, 155-161, (2012). Abstract
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Abstract: An increasing number of high-power laser laboratories are being established with the aim of developing laser-plasma accelerators. Here a short overview is given on the preliminary results obtained in the self-injection test experiment as a part of the commissioning phase of the 220TW FLAME laser facility. For laser energies on target below 1 J and pulse durations around 30 fs, accelerated electron bunches had an energy up the hundred MeV range, showing a significant degree of collimation below 10mrad, in agreement with similar published results and confirming the expected laser performance at this energetic level. A correlation between electron collimation and upshift on laser transmitted light was also observed. © 2012 by Società Italiana di Fisica.

[99] Gizzi L.A., Antonelli L., Atzeni S., Badziak J., Cecchetti C., Chodukowski T., Dubzak R., Giuffrida L., Kalinowska Z., Koester P., Kozlová M., Krousky E., Krus M., Labate L., Levato T., Margarone D., Marocchino A., Moretti A., Nejdl J., O'Dell T., Patria A., Pisarczyk T., Renner O., Ribeyre X., Richetta M., Rosinski M., Rus B., Sawicka M., Skala J., Schiavi A., Schurtz G., Smid M., Spindloe C., Ullshimied J., Wolowski J., Batani D., An experimental study of laser-plasma coupling in a shock-ignition relevant regime, 39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics, 2, 946-949, (2012).
[100] Antonelli L., Batani D., Richetta M., Koester P., Labate L., Levato T., Gizzi L., Krousky E., Skala J., Dubzak R., Ullshimied J., Renner O., Smid M., Rosinski M., Badziak J., Pisarczyk T., Kalinowska Z., Chodukowski T., Reasults in shock ignition experiments at pals: Kα generation and hot electrons study, 39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics, 1, 461-464, (2012).
[101] Malizia A., Lupelli I., D'Amico F., Sassolini A., Fiduccia A., Quarta A.M., Fiorito R., Gucciardino A., Richetta M., Bellecci C., Gaudio P., Comparison of software for rescue operation planning during an accident in a nuclear power plant, Defence S and T Technical Bulletin, 5(1), 36-45, (2012). Abstract
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Abstract: This work has been developed to determine proper analytical support instruments in order to improve emergency operation systems in case of accidents in a nuclear reactor. The case study analysed is in reference to an experimental nuclear fission power plant in Italy (the information about the name and location of this plant has been omitted for safety reasons). The accidental event's consequences were simulated using a free licensed software, HotSpot, and the results obtained were compared with the results obtained using ISPRA Software, the only software certified by the Italian National Institute for Environmental Protection and Research (ISPRA) for nuclear accidents. Once the reliability of HotSpot was established, the most critical incident for this reactor, as indicated by the latest revision of the National Plan on Protective Measures against Nuclear and Radiological Emergencies, was simulated. The simulation results (for areas classified with respect to limits on effective dose) were used as input in the development, through the use of the GeoMedia GIS software, of a vulnerability model that takes into account the spatial distribution of the population in the area affected by the event. In the context of emergency management, such instruments should be integrated with the systems of command & control centres for crisis management and the emergency operation centre (EOC), and made available to the entire chain of emergency management, including the field teams with handheld terminals.

Keywords: Ground deposition | Hotspot | ISPRA software | Nuclear power plant accident scenario | Radiological emergency planning

[102] Gaudio P., Gelfusa M., Richetta M., Preliminary results of a Lidar-Dial integrated system for the automatic detection of atmospheric pollutants, Proceedings of SPIE - The International Society for Optical Engineering, 8534, (2012). Abstract
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Abstract: In the last decades, atmospheric pollution in urban and industrial areas has become a major concern of both developed and developing countries. In this context, surveying relative large areas in an automatic way is an increasing common objective of public health organisations. The Lidar-Dial techniques are widely recognized as a cost-effective approach to monitor large portions of the atmosphere and, for example, they have been successful applied to the early detection of forest fire. The studies and preliminary results reported in this paper concern the development of an integrated Lidar-Dial system able to detect sudden releases in air of harmful and polluting substances. The propose approach consists of continuous monitoring of the area under surveillance with a Lidar type measurement (by means of a low cost system). Once a significant increase in the density of a pollutant is revealed, the Dial technique is used to identify the released chemicals. In this paper, the specifications of the proposed station are discussed. The most stringent requirement is the need for a very compact system with a range of at least 600-700 m. Of course, the optical wavelengths must be in an absolute eye-safe range for humans. A conceptual design of the entire system is described and the most important characteristic of the main elements are provided. In particular the capability of the envisaged laser sources, Nd:YAG and CO2 lasers, to provide the necessary quality of the measurements is carefully assessed. Since the detection of dangerous substances must be performed in an automatic way, the monitoring station will be equipped with an adequate set of control and communication devices for independent autonomous operation. The results of the first preliminary tests illustrate the potential of the chosen approach. © 2012 SPIE.

Keywords: Dial | Lidar | monitoring system | pollutants

[103] Batani D., Malka G., Schurtz G., Ribeyre X., Lebel E., Giuffrida L., Tikhonchuk V., Volpe L., Patria A., Koester P., Labate L., Gizzi L.A., Antonelli L., Richetta M., Nejdl J., Sawicka M., Margarone D., Krus M., Krousky E., Skala J., Dudzak R., Velyhan A., Ullshmied J., Renner O., Smid M., Klimo O., Atzeni S., Marocchino A., Schiavi A., Spindloe C., O'Dell T., Vinci T., Wolowski J., Badziak J., Pysarcizck T., Rosinski M., Kalinowska Z., Chodukowski T., Preliminary results from recent experiments and future roadmap to shock ignition of fusion targets, Journal of Physics: Conference Series, 399, (2012). Abstract
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Abstract: Shock ignition (SI) is a new approach to Inertial Confinement Fusion (ICF) based on decoupling the compression and ignition phase. The last one relies on launching a strong shock through a high intensity laser spike (≤ 10 16 W/cm2) at the end of compression. In this paper, first we described an experiment performed using the PALS iodine laser to study laser-target coupling and laser-plasma interaction in an intensity regime relevant for SI. A first beam with wavelength λ = 1.33 μm and low intensity was used to create an extended preformed plasma, and a second one with λ = 0.44 μm to create a strong shock. Several diagnostics characterized the preformed plasma and the interaction of the main pulse. Pressure up to 90 Mbar was inferred. In the last paper of the paper, we discuss the relevant steps, which can be followed in order to approach the demonstration of SI on laser facilities like LMJ.

[104] Benedetti M., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Richetta M., Scaled experiment for Loss of Vacuum Accidents in nuclear fusion devices: Experimental methodology for fluid-dynamics analysis in STARDUST facility, Recent Researches in Mechanics - Proc. of the 2nd Int. Conf. on FLUIDSHEAT'11, TAM'11,Proc. of the 4th WSEAS Int. Conf. UPT'11, CUHT'11, 142-147, (2011). Abstract
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Abstract: A recognized safety issue for future fusion reactors fueled with deuterium and tritium is the generation of sizeable quantities of dust. Activated dust mobilization during a Loss of Vacuum Accidents (LOVA) is one of the safety concerns for the International Thermonuclear Experimental Reactor (ITER). Intense thermal loads in fusion devices occur during plasma disruptions, Edge Localized Modes (ELM) and Vertical Displacement Events (VDE). They will result in macroscopic erosion of the plasma facing materials and consequent accumulation of activated dust into the ITER Vacuum Vessel (VV). In order to perform thermo-fluid dynamic analysis a small facility, Small Tank for Aerosol Removal and Dust (STARDUST), was set up at the University of Rome "Tor Vergata", in collaboration with ENEA Frascati laboratories. This facility simulates low pressurization rates (100Pa/s, 300 Pa/s and 500 Pa/s) due to LOVA events in ITER due to a small air inlet at different internal pressure conditions and wall temperatures. The authors will present the experimental results in order to analyze the influence of different pressurization rates in the variation of thermo-fluid dynamic conditions that are strictly connected to dust mobilization.

Keywords: Flow field | ITER | LOVA | Pressurization rate | STARDUST | Velocity

[105] Antonelli L., Batani D., Patria A., Ciricosta O., Labate L., Koester P., Cecchetti C., Gizzi L., Nejdl J., Kozlova M., Rus B., Moretti A., Richetta M., Schurtz G., Study of laser-matter interaction in an intensity regime relevant for shock ignition, 38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts, 35 1, 261-264, (2011).
[106] Batani D., Gizzi L.A., Koester P., Labate L., Honrubia J., Antonelli L., Morace A., Volpe L., Santos J.J., Schurtz G., Hulin S., Ribeyre X., Nicolai P., Vauzour B., Dorchies F., Nazarov W., Pasley J., Richetta M., Lancaster K., Spindloe C., Tolley M., Neely D., Kozlová M., Nejdl J., Rus B., Wolowski J., Badziak J., Experimental results on advanced inertial fusion schemes obtained within the HiPER project, Nukleonika, 57(1), 3-10, (2011). Abstract
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Abstract: This paper presents the results of experiments conducted within the Work Package 10 (fusion experimental programme) of the HiPER project. The aim of these experiments was to study the physics relevant for advanced ignition schemes for inertial confinement fusion, i.e. the fast ignition and the shock ignition. Such schemes allow to achieve a higher fusion gain compared to the indirect drive approach adopted in the National Ignition Facility in United States, which is important for the future inertial fusion energy reactors and for realising the inertial fusion with smaller facilities.

Keywords: Advanced ignition schemes | Cylindrical implosions | Fast ignition | Inertial fusion | Propagation of fast electrons | Shock compressed matter | Shock ignition | Short-pulse ultra-high-intensity laser

[107] Batani D., Koenig M., Baton S., Perez F., Gizzi L.A., Koester P., Labate L., Honrubia J., Antonelli L., Morace A., Volpe L., Santos J., Schurtz G., Hulin S., Ribeyre X., Fourment C., Nicolai P., Vauzour B., Gremillet L., Nazarov W., Pasley J., Richetta M., Lancaster K., Spindloe C., Tolley M., Neely D., Kozlová M., Nejdl J., Rus B., Wolowski J., Badziak J., Dorchies F., The HiPER project for inertial confinement fusion and some experimental results on advanced ignition schemes, Plasma Physics and Controlled Fusion, 53(12), (2011). Abstract
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Abstract: This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to 'advanced ignition schemes', i.e. the fast ignition and the shock ignition approaches to inertial fusion. Such schemes are aimed at achieving a higher gain, as compared with the classical approach which is used in NIF, as required for future reactors, and make fusion possible with smaller facilities. In particular, a series of experiments related to fast ignition were performed at the RAL (UK) and LULI (France) Laboratories and studied the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser-plasma coupling in the 10 16 W cm -2 intensity regime of interest for shock ignition. © 2011 IOP Publishing Ltd.

[108] Gaudio P., Gelfusa M., Lupelli I., Malizia A., Moretti A., Richetta M., Serafini C., Bellecci C., First open field measurements with a portable CO<inf>2</inf> lidar/ dial system for early forest fires detection, Proceedings of SPIE - The International Society for Optical Engineering, 8182, (2011). Abstract
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Abstract: Lidar and dial are well established methods to explore the atmosphere. Different groups have already shown experimentally the possibility to measure the density variation of aerosol and particulate in the atmosphere due to plumes emitted in forest fires with this kind of systems. The aim of the present work is to demonstrate the capabilities of our mobile Lidar system, based on a CO2 laser, to detect forest fires and minimizing false alarms. For this purpose, our system can be operated in both lidar and dial configurations in sequence. The first Lidar measurement is performed to evaluate the variation of the local density into the atmosphere, using a nonabsorption water wavelength 10R18 (10.571 μm). If the returned signal reports a backscattering peak, the presence of a fire is probable. To confirm this hypothesis, a second dial measurement is carried out to reveal a second component emitted during the combustion process. The chosen second component is water vapour, which is, as it is well-known, largely produced during the first combustion stage. Measuring the water concentration peak after the detection of the aerosol density increment (referred to the standard mean atmospheric value) represents a good method to reduce false alarms with a dial system. In order to test this methodology, a first set of measurements has been performed in a field near the Engineering Faculty of the University of Rome "Tor Vergata". A quite small controlled-fire has been lighted into a box at a distance of about one kilometre from the system. The data acquired at the two wavelengths (10R18 and 10R20) have been averaged on 100 elastic backscattered Lidar signals. The first results confirm the effectiveness of the measurement strategy for reducing the number of false alarm preserving the early detection. © 2011 SPIE.

[109] Vauzour B., Santos J.J., Batani D., Baton S.D., Koenig M., Nicolaï P., Perez F., Beg F.N., Benedetti C., Benocci R., Brambrink E., Chawla S., Coury M., Dorchies F., Fourment C., Galimberti M., Gizzi L.A., Heathcote R., Higginson D.P., Honrubia J.J., Hulin S., Jafer R., Jarrot L.C., Labate L., Lancaster K., Köster P., MacKinnon A.J., McKenna P., McPhee A.G., Nazarov W., Pasley J., Ramis R., Rhee Y., Regan C., Ribeyre X., Richetta M., Serres F., Schlenvoigt H.P., Schurtz G., Sgattoni A., Spindloe C., Vaisseau X., Volpe L., Yahia V., Experimental study of fast electron propagation in compressed matter, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 653(1), 176-180, (2011). Abstract
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Abstract: We report on experimental results of the fast electron transport in compressed plasmas, created by laser-induced shock propagation in both cylindrical and planar geometry. Two experiments were carried out. The first one was based on the compression of a polyimide cylinder filled with foams of three different initial densities (ρ0). X-ray and proton radiographies of the target during the compression coupled with hydrodynamic simulations show that the obtained core densities and temperatures range from 2 to 11 g/cm 3 and from 30 to 120 eV, respectively. By studying the K-shell fluorescence from dopant atoms inside the target and from tracer layers situated at both front and rear side of the target it has been possible to investigate the fast electron propagation. The results show that Cu Kα yield emitted by the target rear side foil decreases with increasing compression, independently of ρ0. An electron collimation can also be observed for certain experimental conditions where a convergent resistivity gradient interacts with the fast electron beam. The second experiment was performed in a planar geometry with a compressing shock counter-propagative to the fast electron beam. In this case the areal density ρz seen by the electrons is constant during the compression in such a way that changes in the fast electron range should be ascribed to collective mechanisms. The study of the Kα fluorescence, from buried fluorescent layers of different atomic numbers, shows that the electrons with energy <75keV are more affected by resistive losses in compressed compared to non-compressed targets. These two experiments were part of the Experimental Fusion Validation Program of the HiPER project. © 2010 Elsevier B.V.

Keywords: Compression | Electron transport | Fast Ignition | Hydrodynamic simulations | Proton radiography | X-ray radiography

[110] Bellecci C., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Quaranta R., Richetta M., Validation of a loss of vacuum accident (LOVA) Computational Fluid Dynamics (CFD) model, Fusion Engineering and Design, 86(9-11), 2774-2778, (2011). Abstract
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Abstract: Intense thermal loads in fusion devices occur during plasma disruptions, Edge Localized Modes (ELM) and Vertical Displacement Events (VDE). They will result in macroscopic erosion of the plasma facing materials and consequent accumulation of activated dust into the ITER Vacuum Vessel (VV). A recognized safety issue for future fusion reactors fueled with deuterium and tritium is the generation of sizeable quantities of dust. In case of LOVA, air inlet occurs due to the pressure difference between the atmospheric condition and the internal condition. It causes mobilization of the dust that can exit the VV threatening public safety because it may contain tritium, may be radioactive from activation products, and may be chemically reactive and/or toxic (Sharpe et al. [1]; Sharpe and Humrickhouse [2]). Several experiments have been conducted with STARDUST facility in order to reproduce a low pressurization rate (300 Pa/s) LOVA event in ITER due to a small air leakage for two different positions of the leak, at the equatorial port level and at the divertor port level, in order to evaluate the velocity magnitude in case of a LOVA that is strictly connected with dust mobilization phenomena. A two-dimensional (2D) modelling of STARDUST, made with the CFD commercial code FLUENT, has been carried out. The results of these simulations were compared against the experimental data for CFD code validation. For validation purposes, the CFD simulation data were extracted at the same locations as the experimental data were collected. In this paper, the authors present and discuss the computer-simulation data and compare them with data collected during the laboratory studies at the University of Rome "Tor Vergata" Quantum Electronics and Plasmas lab. © 2011 Elsevier B.V. All rights reserved.

Keywords: CFD | Dust | LOVA

[111] Antonelli L., Batani D., Patria A., Ciricosta O., Cecchetti C.A., Koester P., Labate L., Giulietti A., Gizzi L.A., Moretti A., Richetta M., Giuffrida L., Torrisi L., Kozlová M., Nejdl J., Sawicka M., Margarone D., Rus B., Schurtz G., Ribeyre X., Lafon M., Spindloe C., O'Dell T., Laser-plasma coupling in the shock-ignition intensity regime, Acta Technica CSAV (Ceskoslovensk Akademie Ved), 56(TOPICAL ISSUE), (2011). Abstract
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Abstract: A novel approach to ICF called shock ignition, that relies on delivery of a very strong shock created by a laser pulse at intensities around 10 16 W cm-2, is investigated. In this context, an experiment using two beams from the Prague Asterix Laser System with time duration of 300 ps was performed at the PALS laboratory. The first beam at low intensity was used to create extended preformed plasma, and the second one to create a strong shock. Several diagnostics were used to characterize the preformed plasma and the interaction of the main pulse with the target. © 2011 Institute of Thermomechanics AS CR, v.v.i.

Keywords: Inertial confinement fusion | Laser-driven shock | Parametric instabilities | X-ray deflectometry

[112] Pérez F., Debayle A., Honrubia J., Koenig M., Batani D., Baton S.D., Beg F.N., Benedetti C., Brambrink E., Chawla S., Dorchies F., Fourment C., Galimberti M., Gizzi L.A., Gremillet L., Heathcote R., Higginson D.P., Hulin S., Jafer R., Koester P., Labate L., Lancaster K.L., Mackinnon A.J., Macphee A.G., Nazarov W., Nicolai P., Pasley J., Ramis R., Richetta M., Santos J.J., Sgattoni A., Spindloe C., Vauzour B., Vinci T., Volpe L., Magnetically guided fast electrons in cylindrically compressed matter, Physical Review Letters, 107(6), (2011). Abstract
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Abstract: Fast electrons produced by a 10ps, 160J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. Kα-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter. © 2011 American Physical Society.

[113] Nejdl J., Kozlová M., Sawicka M., Margarone D., Krus M., Prokupek J., Rus B., Batani D., Antonelli L., Patria A., Ciricosta O., Cecchetti C., Koester P., Labate L., Giulietti A., Gizzi L.A., Moretti A., Richetta M., Schurtz G., Ribeyre X., Lafon M., Spindloe C., O'Dell T., Investigation of laser plasmas relevant to shock ignition at PALS, Proceedings of SPIE - The International Society for Optical Engineering, 8080, (2011). Abstract
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Abstract: We present the results of an experiment concerning laser-plasma interaction in the regime relevant to shock ignition. The interaction of high-intensity frequency tripled laser pulse with CH plasma preformed by lower intensity pre-pulse on fundamental wavelength of the kJ-class iodine laser was investigated in the planar geometry in order to estimate the coupling of the laser energy to the shock wave or parametric instabilities such as stimulated Raman or Brillouin scattering, or to the fast electrons. First the complete characterization of the hydrodynamic parameters of preformed plasma was made using crystal spectrometer to estimate the electron temperature and XUV probe to resolve the electron density profile close to the critical density region. The other part of the experiment consisted of the shock chronometry, calorimetry of the back-scattered light and hard X-ray spectrometry to evaluate the coupling to different processes. The preliminary analysis of the measurements showed rather low energy transfer of the high-intensity pulse to back-scattered light (> 5%) and no traces of any significant hot electron production were found in the X-ray spectra. © 2011 SPIE.

Keywords: Inertial confinement fusion | Laser-plasma interaction | Shock ignition | X-ray laser deflectometry

[114] Volpe L., Batani D., Vauzour B., Nicolai P., Santos J.J., Dorchies F., Fourment C., Hulin S., Regan C., Perez F., Baton S., Koenig M., Lancaster K., Galimberti M., Heathcote R., Tolley M., Spindloe C., Koester P., Labate L., Gizzi L.A., Benedetti C., Sgattoni A., Richetta M., Can proton radiography be used to image imploding target in ICF experiments?, Proceedings of SPIE - The International Society for Optical Engineering, 8080, (2011). Abstract
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Abstract: Generation of high intensity and well collimated multi energetic proton beams from laser-matter interaction extend the possibility to use protons as a diagnostic to image imploding target in Inertial Confinement Fusion experiments. An experiment was done at the Rutherford Appleton Laboratory (Vulcan Laser Petawatt laser) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European High Power laser Energy Research facility Project). In the experiment, protons accelerated by a ps-laser pulse were used to radiograph a 220 m diameter cylinder (20 m wall, filled with low density foam), imploded with 200 J of green laser light in 4 symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Detailed comparison with 2D numerical hydro simulations has been done using a Monte Carlo code adapted to describe multiple scattering and plasma effects and with those from hard X-ray radiography. These analysis shows that due to the very large mass densities reached during implosion processes, protons traveling through the target undergo a very large number of collisions which deviate protons from their original trajectory reducing proton radiography resolution. Here we present a simple analytical model to study the proton radiography diagnostic performance as a function of the main experimental parameters such as proton beam energy and target areal density. This approach leads to define two different criteria for PR resolution (called "strong" and "weak" condition) describing different experimental conditions. Finally numerical simulations using both hydrodynamic and Monte Carlo codes are presented to validate analytical predictions. PACS numbers: 52.50.Jm, 52.40.Mj, 52.57.-z, 52.70.Nc, 52.38. © 2011 SPIE.

Keywords: Suggested keywords

[115] Bellecci C., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Quaranta R., Richetta M., Loss of vacuum accident (LOVA): Comparison of computational fluid dynamics (CFD) flow velocities against experimental data for the model validation, Fusion Engineering and Design, 86(4-5), 330-340, (2011). Abstract
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Abstract: A recognized safety issue for future fusion reactors fueled with deuterium and tritium is the generation of sizeable quantities of dust. Several mechanisms resulting from material response to plasma bombardment in normal and off-normal conditions are responsible for generating dust of micron and sub-micron length scales inside the VV (Vacuum Vessel) of experimental fusion facilities. The loss of coolant accidents (LOCA), loss of coolant flow accidents (LOFA) and loss of vacuum accidents (LOVA) are types of accidents, expected in experimental fusion reactors like ITER, that may jeopardize components and plasma vessel integrity and cause dust mobilization risky for workers and public. The air velocity is the driven parameter for dust resuspension and its characterization, in the very first phase of the accidents, is critical for the dust release. To study the air velocity trend a small facility, Small Tank for Aerosol Removal and Dust (STARDUST), was set up at the University of Rome "Tor Vergata", in collaboration with ENEA Frascati laboratories. It simulates a low pressurization rate (300 Pa/s) LOVA event in ITER due to a small air inlet from two different positions of the leak: at the equatorial port level and at the divertor port level. The velocity magnitude in STARDUST was investigated in order to map the velocity field by means of a punctual capacitive transducer placed inside STARDUST without obstacles. FLUENT was used to simulate the flow behavior for the same LOVA scenarios used during the experimental tests. The results of these simulations were compared against the experimental data for CFD code validation. For validation purposes, the CFD simulation data were extracted at the same locations as the experimental data were collected for the first four seconds, because at the beginning of the experiments the maximum velocity values (that could cause the almost complete dust mobilization) have been measured. In this paper the authors present and discuss the computer-simulation data and compare them with data collected in STARDUST. © 2011 Elsevier B.V.

Keywords: CFD | Dust | ITER | LOVA | STARDUST | Velocity

[116] Bellecci C., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Quaranta R., Richetta M., STARDUST experimental campaign and numerical simulations: Influence of obstacles and temperature on dust resuspension in a vacuum vessel under LOVA, Nuclear Fusion, 51(5), (2011). Abstract
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Abstract: Activated dust mobilization during a Loss of Vacuum Accident (LOVA) is one of the safety concerns for the International Thermonuclear Experimental Reactor (ITER). Intense thermal loads in fusion devices occur during plasma disruptions, edge localized modes and vertical displacement events. They will result in macroscopic erosion of the plasma facing materials and consequent accumulation of activated dust into the ITER vacuum vessel (VV). These kinds of events can cause dust leakage outside the VV that represents a high radiological risk for the workers and the population. A small facility, Small Tank for Aerosol Removal and Dust (STARDUST), was set up at the ENEA Frascati laboratories to perform experiments concerning the dust mobilization in a volume with the initial conditions similar to those existing in ITER VV. The aim of this work was to reproduce a low pressurization rate (300 Pa s-1) LOVA event in a VV due to a small air leakage for two different positions of the leak, at the equatorial port level and at the divertor port level, in order to evaluate the influence of obstacles and walls temperature on dust resuspension during both maintenance (MC) and accident conditions (AC) (Twalls = 25 °C MC, 110 °C AC). The dusts used were tungsten (W), stainless steel 316 (SS316) and carbon (C), similar to those produced inside the vacuum chamber in a fusion reactor when the plasma facing materials vaporize due to the high energy deposition. The experimental campaign has been carried out by introducing inside STARDUST facility an obstacle to simulate the presence of objects, such as divertor. In the obstacle a slit was cut to simulate the limiter-divertor gap inside ITER VV. In this paper experimental campaign results are shown in order to investigate how the divertor and limiter-divertor gap influence dust mobilization into a VV. A two-dimensional (2D) modelling of STARDUST was made using the CFD commercial code FLUENT, in order to get a preliminary overview of the fluid dynamics behaviour during a LOVA event and to justify the mobilization data. In addition, a numerical model was developed to compare numerical results with experimental ones. © 2011 IAEA, Vienna.

[117] Vauzour B., Pérez F., Volpe L., Lancaster K., Nicola P., Batani D., Baton S.D., Beg F.N., Benedetti C., Brambrink E., Chawla S., Dorchies F., Fourment C., Galimberti M., Gizzi L.A., Heathcote R., Higginson D.P., Hulin S., Jafer R., Kster P., Labate L., MacKinnon A.J., MacPhee A.G., Nazarov W., Pasley J., Regan C., Ribeyre X., Richetta M., Schurtz G., Sgattoni A., Santos J.J., Laser-driven cylindrical compression of targets for fast electron transport study in warm and dense plasmas, Physics of Plasmas, 18(4), (2011). Abstract
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Abstract: Fast ignition requires a precise knowledge of fast electron propagation in a dense hydrogen plasma. In this context, a dedicated HiPER (High Power laser Energy Research) experiment was performed on the VULCAN laser facility where the propagation of relativistic electron beams through cylindrically compressed plastic targets was studied. In this paper, we characterize the plasma parameters such as temperature and density during the compression of cylindrical polyimide shells filled with CH foams at three different initial densities. X-ray and proton radiography were used to measure the cylinder radius at different stages of the compression. By comparing both diagnostics results with 2D hydrodynamic simulations, we could infer densities from 2 to 11 g/cm 3 and temperatures from 30 to 120 eV at maximum compression at the center of targets. According to the initial foam density, kinetic, coupled (sometimes degenerated) plasmas were obtained. The temporal and spatial evolution of the resulting areal densities and electrical conductivities allow for testing electron transport in a wide range of configurations. © 2011 American Institute of Physics.

[118] Batani D., Koenig M., Baton S., Perez F., Gizzi L.A., Koester P., Labate L., Honrubia J., Debayle A., Santos J., Schurtz G., Hulin S., Ribeyre X., Fourment C., Nicolai P., Vauzour B., Gremillet L., Nazarov W., Pasley J., Tallents G., Richetta M., Lancaster K., Spindloe C., Tolley M., Neely D., Norreys P., Kozlová M., Nejdl J., Rus B., Antonelli L., Morace A., Volpe L., Davies J., Wolowski J., Badziak J., Experimental results performed in the framework of the HiPER European Project, Proceedings of SPIE - The International Society for Optical Engineering, 8080, (2011). Abstract
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Abstract: This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to "Advanced Ignition Schemes", i.e. the Fast Ignition and the Shock Ignition Approaches to Inertial Fusion. Such schemes are aimed at achieving a higher gain, as compared to the classical approach which is used in NIF, as required for future reactors, and making fusion possible with smaller facilities. In particular, a series of experiments related to Fast Ignition were performed at the RAL (UK) and LULI (France) Laboratories and were addressed to study the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser-plasma coupling in the 1016 W/cm2 intensity regime of interest for Shock Ignition. © 2011 SPIE.

Keywords: Advanced ignition schemes | Cylindrical implosions | Fast ignition | Inertial fusion | Propagation of fast electrons | Shock compressed matter | Shock ignition | Short-pulse ultra-high-intensity laser

[119] Volpe L., Jafer R., Vauzour B., Nicolai P., Santos J.J., Dorchies F., Fourment C., Hulin S., Regan C., Perez F., Baton S., Lancaster K., Galimberti M., Heathcote R., Tolley M., Spindloe C., Nazarov W., Koester P., Labate L., Gizzi L.A., Benedetti C., Sgattoni A., Richetta M., Pasley J., Beg F.N., Chawla S., Higginson D.P., MacPhee A.G., Batani D., Proton radiography of cylindrical laser-driven implosions, Plasma Physics and Controlled Fusion, 53(3), (2011). Abstract
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Abstract: We report on the results of a recent experiment at the Rutherford Appleton Laboratory investigating fast electron propagation in cylindrically compressed targets; a subject of interest for fast ignition. This experiment was performed within the framework of the road map of HiPER (the European High Power laser Energy Research facility Project). Protons accelerated by a ps-laser pulse are used to radiograph a 220 νm diameter, imploded with ∼200 J of laser light (1 ns λ = 0.53 νm) in four symmetrically incident beams. Results are also compared with those from hard x-ray radiography. Detailed comparison with 2D radiation hydrodyamics simulations is performed with the aid of a Monte Carlo code adapted to describe plasma effects. Finally, a simple analytical model is developed to estimate the performance of proton radiography for given implosion conditions. © 2011 IOP Publishing Ltd.

[120] Volpe L., Batani D., Vauzour B., Nicolai P., Santos J.J., Regan C., Morace A., Dorchies F., Fourment C., Hulin S., Perez F., Baton S., Lancaster K., Galimberti M., Heathcote R., Tolley M., Spindloe C., Koester P., Labate L., Gizzi L.A., Benedetti C., Sgattoni A., Richetta M., Pasley J., Beg F., Chawla S., Higginson D.P., MacPhee A.G., Proton radiography of laser-driven imploding target in cylindrical geometry, Physics of Plasmas, 18(1), (2011). Abstract
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Abstract: An experiment was done at the Rutherford Appleton Laboratory (Vulcan laser petawatt laser) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European high power laser energy research facility project). In the experiment, protons accelerated by a picosecond-laser pulse were used to radiograph a 220 μm diameter cylinder (20 μm wall, filled with low density foam), imploded with ∼200 J of green laser light in four symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Results are also compared to those from hard x-ray radiography. Detailed comparison with two-dimensional numerical hydrosimulations has been done using a Monte Carlo code adapted to describe multiple scattering and plasma effects. Finally we develop a simple analytical model to estimate the performance of proton radiography for given implosion conditions. © 2011 American Institute of Physics.

[121] Bellecci C., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Quaranta R., Richetta M., Experimental mapping of velocity flow field in case of L.O.V.A inside stardust facility, 37th EPS Conference on Plasma Physics 2010, EPS 2010, 2, 703-706, (2010).
[122] Bellecci C., Gaudio P., Gelfusa M., Lo Feudo T., Murari A., Richetta M., De Leo L., In-cell measurements of smoke backscattering coefficients using a CO <inf>2</inf> laser system for application to lidar-dial forest fire detection, Optical Engineering, 49(12), (2010). Abstract
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Abstract: In the lidar-dial method, the amount of the water vapor present in the smoke of the vegetable fuel is detected to reduce the number of false alarms. We report the measurements of the smoke backscattering coefficients for the CO2 laser lines 10R20 and 10R18 as determined in an absorption cell for two different vegetable fuels (eucalyptus and conifer). These experimental backscattering coefficients enable us to determine the error to be associated to the water vapor measurements when the traditional first-order approximation is assumed. We find that this first-order approximation is valid for combustion rates as low as 100 gs. © 2010 Society of Photo-Optical Instrumentation Engineers.

Keywords: backscattering coefficient | dial | forest fire | water vapor

[123] Bellecci C., Gaudio P., Gelfusa M., Malizia A., Richetta M., Serafini C., Ventura P., Planetary Boundary Layer (PBL) monitoring by means of two laser radar systems: Experimental results and comparison, Proceedings of SPIE - The International Society for Optical Engineering, 7832, (2010). Abstract
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Abstract: The PBL is the lower layer of the atmosphere that is sensitive to the effect of the Earths surface, it controls the flow of heat and momentum between the surface and the free atmosphere, thus playing a key role in atmospheric circulation. At University of Rome "Tor Vergata", Quantum Electronic and Plasma Laboratories (EQP), two mobile Light Detection and Ranging (LIDAR) systems have been developed. With these systems the monitoring of the Planetary Boundary Layer (PBL) has been performed. The first mobile Lidar system is based on a pulsed Nd:YAG Q-Switched laser source operating at three wavelengths: 1064 nm, 532 nm and 355 nm. Acquiring the elastic backscattered signals, it has been possible to estimate the aerosolitic backscattering coefficient at the aim to reconstruct the vertical aerosol profiles. The second one is a Differential Absorption Lidar system (DIAL), composed by a CO2 laser, working in the window spectral range between 9 and 11μm. With this system it has been estimated the water vapour concentration in the PBL region using the two wavelengths 10R20 (10.591 μm) and 10R18 (10.571 μm), which represent, respectively, the absorbing wavelength and non-absorbing one of the water molecule. The comparison of the backscattered radiation at these wavelengths yields the trace gas number density as a function of distance along the field-of-view of the receiving telescope. Diurnal and nocturnal measurements have been performed simultaneity using the two Lidar/Dial systems. Vertical profiles of the aerosolitic backscattering coefficient and water vapour concentration profiles have been estimated. The results and their comparison will be present in this work. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Keywords: aerosol | DIAL | Lidar | Nd:YAG | PBL | TE CO laser 2 | water vapour

[124] Montereali R.M., Almaviva S., Bonfigli F., Cricenti A., Faenov A., Flora F., Gaudio P., Lai A., Martellucci S., Nichelatti E., Pikuz T., Reale L., Richetta M., Vincenti M.A., Lithium fluoride thin-film detectors for soft X-ray imaging at high spatial resolution, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 623(2), 758-762, (2010). Abstract
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Abstract: Among insulating materials containing point defects, lithium fluoride (LiF) is a radiation-sensitive alkali halide well known in dosimetry and as active medium in light-emitting devices and lasers. Electronic point defects can be produced in LiF crystals and films by different kinds of radiation. Some of these electronic defects, known as colour centres, are optically active, with broad absorption and emission bands in the visible spectral range. Novel thin-film imaging detectors for extreme ultraviolet and soft X-rays, based on photoluminescence from aggregated colour centres in LiF, have been proposed and are currently under development, successfully extending their operation also in the hard X-ray region, up to 10 keV. Among the main peculiarities of LiF-based detectors, there are intrinsic high spatial resolution, in principle limited only by the point defect size, large field of view and wide dynamic range. These imaging detectors feature great versatility, as they can be grown in the form of thin films on different substrates by well-assessed physical deposition techniques. We present the promising results obtained using different X-ray laserplasma sources in the field of nanotechnology, biology and in material science in view of future perspectives of research and development.© 2010 Elsevier B.V. All rights reserved.

Keywords: Colour centres | Lithium fluoride | Photoluminescence | Thin films | X-ray imaging detector

[125] Jafer R., Volpe L., Batani D., Koenig M., Baton S., Brambrink E., Perez F., Dorchies F., Santos J.J., Fourment C., Hulin S., Nicolai P., Vauzour B., Lancaster K., Galimberti M., Heathcote R., Tolley M., Spindloe C., Koester P., Labate L., Gizzi L., Benedetti C., Sgattoni A., Richetta M., Pasley J., Beg F., Chawla S., Higginson D., Mackinnon A., Mcphee A., Kwon D.H., Rhee Y., Proton radiography and fast electron propogation through cyliderically compressed targets, Journal of the Korean Physical Society, 57(21), 305-310, (2010). Abstract
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Abstract: The paper describes the key points contained in the short term HiPER, (High Power laser Energy Research) experimental road map, as well as the results of two phases of the experiment performed in "HiPER, dedicated time slots. Experimental and theoretical results of relativistic electron transport in cylindrically compressed matter are presented. This experiment was achieved at the VULCAN laser facility (UK) by using four long pulse beams (∼4 x 50 J, 1 ns, at 0.53 μm) to compress a hollow plastic cylinder filled with plastic foam of three different densities (0.1, 0.3, and 1 g cm-3). In the first phase of the experiment, protons accelerated by a, picosecond laser pulse were used to radiograph a, cylinder filled with 0.1 g/cc foam. Point projection proton backlighting was used to measure the degree of compression as well as the stagnation time. Results were compared to those from hard X-ray radiography. Finally, Monte Carlo simulations of proton propagation in cold and compressed targets allowed a detailed comparison with 2D numerical hydro simulations. 2D simulations predict a, density of 2-5 g cm-3 and a plasma temperature up to 100 eV at maximum compression. In the second phase of the experiment, a short pulse (10ps, 160 J) beam generated fast electrons that propagated through the compressed matter by irradiating a nickel foil at an intensity of 5 X 1018 Wcm-2. X-ray spectrometer and imagers were implemented in order to estimate the compressed plasma conditions and to infer the hot electron characteristics. Results are discussed and compared with simulations.

Keywords: Electron transport | ICF | Proton radiography | X-ray radiography

[126] Jafer R., Volpe L., Batani D., Koenig M., Baton S., Brambrink E., Perez F., Dorchies F., Santos J.J., Fourment C., Hulin S., Nicolai P., Vauzour B., Lancaster K., Galimberti M., Heathcote R., Tolley M., Spindloe C., Koester P., Labate L., Gizzi L., Benedetti C., Sgattoni A., Richetta M., Pasley J., Beg F., Chawla S., Higginson D., MacKinnon A., McPhee A., Kwon D.H., Ree Y., Proton radiography of a laser-driven cylindrical implosion, AIP Conference Proceedings, 1209, 47-50, (2010). Abstract
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Abstract: A recent experiment was performed at the Rutherford Appleton Laboratory (UK) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This experiment was performed in the framework of the experimental road map of the Hiper project (the European High Power laser Energy Research facility Project). In this experiment, protons accelerated by a pecosecond laser pulse have been used to radiograph a 220μm-diameter, 20μm-wall cylinder filled with 0.1 g/cc foam, imploded with ∼200 J of green laser light in 4 symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to measure the compression degree as well as the stagnation time. Results were compared to those from hard X-ray radiography. Finally, Monte Carlo simulations of proton propagation in the cold and in the compressed targets allowed a detailed comparison with 2D numerical hydro simulations. © 2010 American Institute of Physics.

Keywords: ICF | Laser based proton radiography

[127] Ciricosta O., Labate L., Atzeni S., Barbini A., Batani D., Benocci R., Cornolti F., Galimberti M., Gaudio P., Giulietti D., Gizzi L.A., Martellucci S., Richetta M., Schiavi A., Vaselli M., Giulietti A., BLISS@CNR-Pisa: A flexible laser for small scale test experiments on fusion oriented physics, AIP Conference Proceedings, 1209, 23-26, (2010). Abstract
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Abstract: By the year 2010 a new laser will be operational at the CNR Campus in Pisa. The laser system will deliver two beams each one providing 1-ns 50-joule pulses of high optical quality and full control of phase. The major feature of the system is its spectral and time shape flexibility ranging from narrowband single mode operation to broadband operation with pulse tailoring. According to previous experiments and recent simulations, these features could critically determine the laser-pellet coupling in the different approaches to laser fusion. The physics involved in the different coupling processes is still not fully investigated experimentally. The BLISS laser, combined with the rest of the ILIL experimental facility, including ultrafast optical probing, time resolved optical X-ray diagnostics and particle detection could contribute to this investigation with ad hoc small scale experiments. The main features of the innovative BLISS laser front end for broadband operation are shown, together with the amplification chain and the main features of the experimental installation. Data from simulations providing a useful input for future experiments are also presented. BLISS is expected to contribute to the preparatory phase of the large scale European HiPER project. © 2010 American Institute of Physics.

Keywords: Broadband laser | ICF | OPCPA

[128] Vauzour B., Koenig M., Batani D., Baton S., Beg F.N., Benedetti C., Brambrink E., Chawla S., Dorchies F., Fourment C., Galimberti M., Gizzi L.A., Heathcote R., Higginson D.P., Hulin S., Jafer R., Köster P., Labate L.L., Lancaster K.L., MacKinnon A.J., MacPhee A.G., Nazarov W., Nicola P.H., Pasley J., Perez F., Ribeyre X., Richetta M., Santos J.J., Schurtz G., Sgattoni A., Spindloe C., Volpe L., X-ray diagnostics of fast electrons propagation in high density plasmas obtained by cylindrical compression, Journal of Physics: Conference Series, 244(PART 2), (2010). Abstract
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Abstract: We report on X-ray diagnostics results from an experiment on fast electrons propagation in cylindrically compressed targets. It was performed on the VULCAN TAW laser facility at RAL (UK) using four long pulses (1ns, 70 J each at 2ω) to compress a cylindrical polyimide target filled with CH foam at 3 different initial densities. The cylindrical geometry allows us to reach temperatures and densities higher than those obtained in planar geometry compression. 2D hydrodynamic simulations predicted a core density range from 4 to 8 g/cm3 and a core temperature from 30 eV up to 175 eV at maximum compression. An additional short laser pulse (10 ps, 160 J at ω) was focused on a Ni foil at one of the cylinder edges in order to generate a fast electrons current propagating along the compressed target. A X-ray radiography diagnostic was implemented in order to estimate the core plasma conditions of the compressed cylinder. Moreover two Bragg X-ray spectrometers collected the Kα fluorescence from the target so as to determine the variations of fast electrons population during the compression. © 2010 IOP Publishing Ltd.

[129] Bellecci C., Gaudio P., Lupelli I., Malizia A., Porfiri M.T., Quaranta R., Richetta M., Characterization of divertor influence in case of LOVA: CFD analysis of stardust experimental facility, 36th EPS Conference on Plasma Physics 2009, EPS 2009 - Europhysics Conference Abstracts, 33 E1, 266-269, (2009).
[130] Jafer R., Volpe L., Batani D., Koenig M., Baton S., Bambrink E., Perez F., Dorchies F., Santos J., Fourment C., Hulin S., Nicolai P., Vauzour B., Lancaster K., Galimberti M., Heathcote R., Koester P., Labate L., Gizzi L., Benedetti C., Sgattoni A., Richetta M., Pasley J., Beg F., Chawla S., Higginson D., MacKinnon A., McPhee A., Proton radiography of a cylindrical laser-driven implosion, IEEE International Conference on Plasma Science, (2009).
[131] Bellecci C., Gaudio P., Gelfusa M., Lo Feudo T., Malizia A., Richetta M., Ventura P., Raman water vapour concentration measurements for reduction of false alarms in forest fire detection, Proceedings of SPIE - The International Society for Optical Engineering, 7479, (2009). Abstract
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Abstract: Forest fires can be the cause of environmental catastrophe, with the natural outcomes of serious ecological and economic damages, together with the possibility to endanger human safety. At the aim to reduce this catastrophe several author have been shown that the Laser light scattering can be uses to reveals the particulate emitted in the smoke. Infact experimental and theoretical investigations have shown that lidar is a powerful tool to detect the tenuous smoke plumes produced by forest fires at an early stage. In early 90's Arbolino and Andreucci have shown the theoretical possibility to detect the particulate emitted in atmosphere from smoke forest fire. Vilar at all have shown experimentally the possibility to measure the density variation in atmosphere due to plume emitted in forest fire event. Gaudio at all. have already shown that it is possible to evaluate water vapor emitted in smoke of vegetable fuel using a CO2 dial system. In this paper a theoretical model to evaluate the capabilities of a lidar system in fire surveillance of wooded areas will be presented. In particular we intend propose a technique to minimizing the false alarm in the detection of forest fire by lidar based on a measurement of second components emitted in a combustion process. Usually to detect a fire alarm a rapid increase of aerosol amount is measured. If the backscattering signal report a peak, the presences of a forest fire will be probable. Our idea to confirm this hypothesis is measure the second components emitted in a forest fire at the aim to minimize the false alarm. The simulated measurements of the humidity amount within the smoke plume will be carried out by means of Raman analysis. Fixing the burning rate of the vegetable-fuels, the maximum range of detection will be evaluated. © 2009 SPIE.

[132] Bellecci C., De Leo L., Gaudio P., Gelfusa M., Lo Feudo T., Martellucci S., Richetta M., Reduction of false alarms in forest fire surveillance using water vapour concentration measurements, Optics and Laser Technology, 41(4), 374-379, (2009). Abstract
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Abstract: In this work a theoretical model to evaluate the capabilities of our lidar system in forest fire detection is reported. In particular, a new idea of minimization of false alarm is shown. In a forest fire, in fact, a lot of ashes and in the first stage a large amount of water vapour are emitted. Measurements of water vapour increase with respect to standard humidity in the atmosphere due to a forest fire event, by means of Raman analysis, permit to minimize the false alarm. A simulation of one case of study permits to estimate the maximum range of detection and minimum sensibility of our lidar system. In this paper the theoretical results are shown. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Forest fire | Lidar | Raman technique

[133] Bonfigli F., Almaviva S., Baldacchini G., Flora F., Lai A., Montereali R.M., Vincent M.A., Cricenti A., Oliva C., Ustione A., Faenov A., Pikuz T., Reale L., Gaudio P., Martellucci S., Richetta M., High-resolved fluorescence imaging of X-ray micro-radiographies on novel LiF detectors, Proceedings of the Workshop on Synchrotron Radiation and Nanostructures - Papers in Honour of Paolo Perfetti, 40-47, (2009). Abstract
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Abstract: A novel X-ray imaging detector based on optical reading of photoluminescent color centers in lithium fluoride, LiF, is presented. Its main characteristics - i.e. high spatial resolution on a large field of view, wide dynamic range, versatility and simplicity of use - make it a high performance imaging detector for applications in X-ray microscopy, photonic devices, Extreme UltraViolet (EUV) lithography, and materials science, as well as in the characterization of intense X-ray sources, including Free Electron Laser (FEL). The peculiarities of the LiF imaging detector overcome some of the limitations of other commonly used ones, and can be exploited for X-ray microscopy in very simple configurations, such as lensless techniques, even for in vivo investigations of biological samples. Advanced optical microscopy techniques have been used to obtain highly-resolved microradiographies of biological specimens, performed in absorption contrast mode. Its peculiarities seem suitable also for use in phase-contrast experiments. The LiF-based detector versatility allows improvements in order to optimize its response and sensitivity. © 2009 World Scientific Publishing Co. Pte. Ltd.

[134] Perez F., Koenig M., Batani D., Baton S.D., Beg F.N., Benedetti C., Brambrink E., Chawla S., Dorchies F., Fourment C., Galimberti M., Gizzi L.A., Heathcote R., Higginson D.P., Hulin S., Jafer R., Koester P., Labate L., Lancaster K., MacKinnon A.J., McPhee A.G., Nazarov W., Nicolai P., Pasley J., Ravasio A., Richetta M., Santos J.J., Sgattoni A., Spindloe C., Vauzour B., Volpe L., Fast-electron transport in cylindrically laser-compressed matter, Plasma Physics and Controlled Fusion, 51(12), (2009). Abstract
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Abstract: Experimental and theoretical results of relativistic electron transport in cylindrically compressed matter are presented. This experiment, which is a part of the HiPER roadmap, was achieved on the VULCAN laser facility (UK) using four long pulses beams (∼4 × 50 J, 1 ns, at 0.53 νm) to compress a hollow plastic cylinder filled with plastic foam of three different densities (0.1, 0.3 and 1 g cm-3). 2D simulations predict a density of 2-5 g cm-3 and a plasma temperature up to 100 eV at maximum compression. A short pulse (10 ps, 160 J) beam generated fast electrons that propagate through the compressed matter by irradiating a nickel foil at an intensity of 5 × 1018 W cm-2. X-ray spectrometer and imagers were implemented in order to estimate the compressed plasma conditions and to infer the hot electron characteristics. Results are discussed and compared with simulations. © 2009 IOP Publishing Ltd.

[135] Bellecci C., Gaudio P., Gelfusa M., Martellucci S., Richetta M., Ventura P., Antonucci A., Pasquino F., Ricci V., Sassolini A., Database for chemical weapons detection: First results, Proceedings of SPIE - The International Society for Optical Engineering, 7116, (2008). Abstract
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Abstract: The quick increase of terrorism and asymmetric war is leading towards new needs involving defense and security. Nowadays we have to fight several kind of threats and use of chemical weapons against civil or military objectives is one of the most dangerous. For this reason it is necessary to find equipment, know-how and information that are useful in order to detect and identify dangerous molecules as quickly and far away as possible, so to minimize damage. Lidar/Dial are some of the most powerful optical technologies. Dial technology use two different wavelengths, in order to measure concentration profile of an investigated molecule. For this reason it is needed a "fingerprint" database which consists of an exhaustive collection of absorption coefficients data so to identify each molecule avoiding confusion with interfering ones. Nowadays there is not such a collection of data in scientific and technical literature. We used an FT-IR spectrometer and a CO2 laser source for absorption spectroscopy measurements using cells filled with the investigated molecules. The CO2 source is the transmitter of our DIAL facility. In this way we can make a proper "fingerprint" database necessary to identify dangerous molecules. The CO2 laser has been chosen because it is eye safe and, mainly, because it covers a spectral band where there is good absorption for this kind of molecules. In this paper IR spectra of mustard will be presented and compared to other substances which may interfere producing a false alarm. Methodology, experimental setup and first results are described. © 2008 SPIE.

Keywords: Cell | Chemical weapons | CO laser 2 | Dial | Fingerprint | IR spectroscopy | Lidar

[136] Reale L., Bonfigli F., Lai A., Flora F., Poma A., Albertano P., Bellezza S., Montereali R.M., Faenov A., Pikuz T., Almaviva S., Vincenti M.A., Francucci M., Gaudio P., Martellucci S., Richetta M., X-ray microscopy of plant cells by using LiF crystal as a detector, Microscopy Research and Technique, 71(12), 839-848, (2008). Abstract
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Abstract: A lithium fluoride (LiF) crystal has been utilized as a new soft X-ray detector to image different biological samples at a high spatial resolution. This new type of image detector for X-ray microscopy has many interesting properties: high resolution (nanometer scale), permanent storage of images, the ability to clear the image and reuse the LiF crystal, and high contrast with greater dynamic range. Cells of the unicellular green algae Chlamydomonas dysosmos and Chlorella sorokiniana, and pollen grains of Olea europea have been used as biological materials for imaging. The biological samples were imaged on LiF crystals by using the soft X-ray contact microscopy and contact micro-radiography techniques. The laser plasma soft X-ray source was generated using a Nd:YAG/Glass laser focused on a solid target. The X-ray energy range for image acquisition was in the water-window spectral range for single shot contact microscopy of very thin biological samples (single cells) and around 1 keV for multishots microradiography. The main aim of this article is to highlight the possibility of using a LiF crystal as a detector for the biological imaging using soft X-ray radiation and to demonstrate its ability to visualize the microstructure within living cells. © 2008 Wiley-Liss, Inc.

Keywords: Algae | Contact microscopy | Micro-radiography | Pollen | Soft X-rays

[137] Oliva C., Ustione A., Almaviva S., Baldacchini G., Bonfigli F., Flora F., Lai A., Montereali R.M., Faenov A.Y., Pikuz T.A., Francucci M., Gaudio P., Martellucci S., Richetta M., Reale L., Cricenti A., SNOM images of X-ray radiographs at nano-scale stored in a thin layer of lithium fluoride, Journal of Microscopy, 229(3), 490-495, (2008). Abstract
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Abstract: In this work, we report a method to observe soft X-ray radiographs at nanoscale of various kind of samples, biological and metallic, stored in a thin layer of lithium fluoride, employing scanning near-field optical microscopy with an optical resolution that reaches 50 nm. lithium fluoride material works as a novel image detector for X-ray nano-radiographs, due to the fact that extreme ultraviolet radiation and soft X-rays efficiently produce stable point defects emitting optically stimulated visible luminescence in a thin surface layer. The bi-dimensional distribution of the so-created defects depends on the local nanostructure of the investigated sample. © 2008 The Authors.

Keywords: High resolution | LiF detector | SNOM | X-ray radiographs

[138] Bellecci C., De Leo L., Gaudio P., Gelfusa M., Lo Feudo T., Martellucci S., Richetta M., Evolution study of smoke backscattering coefficients in a cell by means of a compact mobile Nd:YAG lidar system, Proceedings of SPIE - The International Society for Optical Engineering, 6745, (2008). Abstract
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Abstract: Detection of smoke from forest fire is one of the practical applications of lidar. As it is well known, smoke contains a large number of small particles of ash or soot, leading to a large backscattering efficiency and consequently favourable conditions for lidar application. We have developed a compact mobile lidar system based on Nd:YAG Q-Switched laser source, operating at three wavelengths: 1064 nm, 532 nm and 355 nm, with emission rate of 10 Hz and pulse duration equal to 5 ns when the laser operate at the fundamental harmonic and 4 ns for the second and the third ones. The system has been tested by experimental measurements of the smoke backscattering coefficients carried out in an ad hoc cell. Since the spatial resolution of laser pulse is smaller than the cell length it has been possible to evaluate the profile of the smoke backscattering coefficients inside the cell itself. Moreover it has been developed a computational model for simulating the temporal and spatial evolution of smoke within the cell. These experimental and theoretical data have been used to optimize the theoretical already developed to study the smoke evolution into the atmosphere. In this paper measurements of smoke backscattering coefficients into a cell and simulations of smoke evolution will be presented.

Keywords: Cell | Forest fire | Lidar | Nd:YAG laser | Smoke backscattering coefficient

[139] Bonfigli F., Faenov A., Flora F., Francucci M., Gaudio P., Lai A., Martellucci S., Montereali R.M., Pikuz T., Reale L., Richetta M., Vincenti M.A., Baldacchini G., High-resolution water window X-ray imaging of in vivo cells and their products using LiF crystal detectors, Microscopy Research and Technique, 71(1), 35-41, (2008). Abstract
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Abstract: High contrast imaging of in vivo Chlorella sorokiniana cells with submicron spatial resolution was obtained with a contact water window X-ray microscopy technique using a point-like, laser-plasma produced, water-window X-ray radiation source, and LiF crystals as detectors. This novel type of X-ray imaging detectors is based on photoluminescence of stable electronic point defects, characterized by high intrinsic resolution. The fluorescence images obtained on LiF crystals exposed in single-shot experiments demonstrate the high sensitivity and dynamic range of this new detector. The powerful performances of LiF crystals allowed us to detect the exudates of Chlorella cells in their living medium and their spatial distribution in situ, without any special sample preparation. © 2007 Wiley-Liss, Inc.

Keywords: Color centers | Imaging detectors | Lithium fluoride | X-ray microscopy

[140] Bellecci C., Francucci M., Gaudio P., Gelfusa M., Martellucci S., Richetta M., Lo Feudo T., Application of a CO<inf>2</inf> dial system for infrared detection of forest fire and reduction of false alarm, Applied Physics B: Lasers and Optics, 87(2), 373-378, (2007). Abstract
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Abstract: Forest fires can be the cause of serious environmental and economic damages. For this reason considerable effort has been directed toward forest protection and fire fighting. The means traditionally used for early fire detection mainly consist in human observers dispersed over forest regions. A significant improvement in early warning capabilities could be obtained by using automatic detection apparatus. In order to early detect small forest fires and minimize false alarms, the use of a lidar system and dial technique will be considered. A first evaluation of the lowest detectable concentration will be estimated by numerical simulation. The theoretical model will also be used to get the capability of the dial system to control wooded areas. Fixing the burning rate for several fuels, the maximum range of detection will be evaluated. Finally results of simulations will be reported. © Springer-Verlag 2007.

[141] Bellecci C., De Leo L., Gaudio P., Gelfusa M., Lo Feudo T., Martellucci S., Richetta M., Water vapour emission in vegetable fuel: Absorption cell measurements and detection limits of our CO2 Dial system, Proceedings of SPIE - The International Society for Optical Engineering, 6367, (2006). Abstract
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Abstract: Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO2 Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.

[142] Martellucci S., Bellecci C., Francucci M., Gaudio P., Richetta M., Toscano D., Rydzy A., Gelfusa M., Ciuffa P., Soft x-ray generation by a tabletop Nd:YAG/glass laser system, Journal of Physics Condensed Matter, 18(33), (2006). Abstract
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Abstract: The advent and development of ultra-intense tabletop laser systems has played a significant role in recent decades thanks to the wide number of applications and studies in which these systems were demonstrated to be appropriate. Among these, one of the main applications of ultra-intense radiation is generation of plasma by solid, liquid or gaseous targets. The by-product of x-radiation found many different applications such as spectroscopy, imaging, microlithography, microscopy, radiographies (in particular of biological samples), radiation-matter interaction, fundamental plasma parameter determination, astrophysics, inertial confinement fusion, high energy physics, quantum electrodynamics, and many others. In the following a brief description of our tabletop Nd:YAG/glass apparatus (facility of the Quantum Electronic and Plasma Laboratory of the University of Rome 'Tor Vergata'), together with x-ray conversion efficiency studies for different targets, are reported. © 2006 IOP Publishing Ltd.

[143] Bellecci C., Coniglio L., Francucci M., Gaudio P., Martellucci S., Nanni D., Richetta M., Terra F., Laser-plasma soft-X-rays analysis by means of a CCD camera: A first application to digital micro-radiography, Nuovo Cimento della Societa Italiana di Fisica B, 121(8), 811-822, (2006). Abstract
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Abstract: At the QEP (Quantum Electronics and Plasma) Laboratory of the University of Rome "Tor Vergata", a tabletop ultra intense pulsed source has been applied to generate, among others, soft-X-ray radiation. The source consists of a Q-switched ultra intense multistage Nd:YAG/Glass laser (λ = 1064 nm, I ≅ 1013W/cm2), whose radiation is focused by a triplet upon heavy metal target in order to produce plasma. A CCD framing camera has been set up to measure the X-ray energy of this plasma source (from 0.4 keV up to about 5 keV) and to image X-ray absorption by thin biological samples. This CCD camera, with high sensitivity, high resolution, optimized for very low flux imaging (visible and X-rays) and spectroscopy, employs a 2k × 2k device (astronomical grade, 15 μm pixel-size), controlled by the SDSU (San Diego State University) electronic driver, that is cooled (T = -50°C) by means of a TEC (Thermo-Electric Cooler) cryostat to reduce generation of dark current. In the paper the experimental apparatus is described and preliminary results are shown. © Società Italiana di Fisica.

[144] Bellecci C., Francucci M., Gaudio P., Gelfusa M., Martellucci S., Richetta M., Early detection of small forest fire by dial technique, Proceedings of SPIE - The International Society for Optical Engineering, 5976, (2005). Abstract
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Abstract: Forest fires can be the cause of serious environmental and economic damages. For this reason considerable effort has been directed toward forest protection and fire fighting. The means traditionally used for early fire detection mainly consist in human observers dispersed over forest regions. A significant improvement in early warning capabilities could be obtained by using automatic detection apparatus. In order to early detect small forest fires, the use of a dial system will be considered. A first evaluation of the lowest detectable concentration will be estimated by a numerical simulation. The theoretical model will be used also to get the capacities of a dial system in fire surveillance of wooded areas. Fixing the burning rate for several fuels, the maximum range of detection will be evaluated. The results of these simulations will be reported in the paper.

[145] Bellecci C., Gaudio P., Martellucci S., Penco E., Richetta M., Active clipping system for transversely exited CO<inf>2</inf> lasers, Review of Scientific Instruments, 76(2), (2005). Abstract
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Abstract: A simple intracavity system, based on electrical discharge, is used to control the shape and duration of transverse electric CO2 laser pulses. The clipping mechanism is based on active locking at the same frequency of the laser. The clipping apparatus can deliver gain switched spikes pulses between the temporal range of 100-110 ns. The peak power of the clipped signal is not reduced. The system is optimized to obtain a maximum efficiency equal to 1, and a jitter value of about 10 ns. In the article the characteristics of electrical system are described. Finally a scheme of the apparatus and experimental results are presented. © 2005 American Institute of Physics.

[146] Avollo E., Bellecci C., Casella L., Federico S., Lo Feudo T., Gaudio P., Martellucci S., Richetta M., On the assimilation of water vapour lid ar measurements: A case study, European Space Agency, (Special Publication) ESA SP, 2(561), 657-660, (2004). Abstract
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Abstract: In this paper we show the improvements of assimilating water vapour data into a LAM (Limited Area Model) for a case study of a meteorological event over Calabria, the southernmost tip of Italian peninsula, and we show how Lidar could contribute to give better results. The case study here presented is named "Soverato flood" and represents a prolonged and intense precipitation event. We will discuss this event using ECMWF analysis/forecast cycle as dynamical boundary conditions for RAMS (Regional Atmospheric Modeling System) integration. Two simulations are compared: first one is made using RAMS model without assimilation of water vapour data, the second starts from a RAMS pre-run that assimilates precipitable water data.

[147] Bellecci C., D'Aquila G., Gabriele S., Gaudio P., Martellucci S., Ribecco G., Richetta M., Comparison of columnar water vapour measurements using the Co<inf>2</inf> DIAL method and GPS data analysis, Proceedings of SPIE - The International Society for Optical Engineering, 5232, 521-527, (2004). Abstract
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Abstract: Two remote sensing techniques used to measure water vapour content in the atmosphere are presented: the Lidar/Dial technique and the GPS data analysis method. The dial method, as is well known, can be used to obtain range resolved measurements or an average concentration measurement on the long path using a target topographic method. This methodology permits measurement of the concentration of atmospheric trace gases and, in particular, water vapour profiles. The second remote sensing method is based on an application of the GPS (Global Positioning System). It enables the assessment of the signal propagation delay from satellites to ground-based receivers. Once ground temperature and atmospheric pressure are measured and the GPS signal delay is known, then an estimate of the columnar water vapour content can be performed. In this paper a comparison between the two remote sensing techniques of water vapour measurement are present.

Keywords: Dial | GPS | Lidar | Water vapour

[148] Bellecci C., Bellucci I., Gaudio P., Martellucci S., Petrocelli G., Richetta M., Clipping the tail of a TE-CO<inf>2</inf> laser pulse using a gas breakdown technique for high resolution chemical plume detection, Review of Scientific Instruments, 74(2), 1064-1069, (2003). Abstract
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Abstract: A spark-induced plasma shutter, working in free atmosphere was presented to clip off the nitrogen tail of a TE carbon dioxide laser source. The output laser beams passed through a confocal system realized with two ZnSe lenses, whose focal lengths were 50 mm. The discharge produced in open air provided the means to initiate the plasma, at the passage of the laser beam. Gain switched spike pulses ranging between 100 and 115 ns were obtained at 10P20-laser line.

[149] Bellecci C., Casella L., Federico S., Gaudio P., Lo Feudo T., Martellucci S., Richetta M., Evolution study of a water vapour plume using a mobile CO<inf>2</inf> DIAL System, Proceedings of SPIE - The International Society for Optical Engineering, 4539, 180-190, (2002). Abstract
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Abstract: The DIAL system and the HYPACT model are two useful, means to study plume evolution and dispersion. We developed a mobile DIAL system, mounted onto a truck. The DIAL is based on a single TEA CO2 laser source, able to switch between the "on" and "off" lines. This set-up allows rapid tuning of the two lines and keeps the misalignment within a range of 0.1 mrad, moderately below the beam divergence. The receiving system is a Newtonian telescope. All the instrumentation and the telescope are located inside the van. A large size scanning mirror, installed on the roof, sends the laser radiation into the atmosphere and, at the same time, it collects the backscattered light. To test all instrumentation, preliminary measurements have been completed to monitor a water vapour plume of a cement factory. The measurements are qualitatively compared against a dispersion plume model run initialially from climatological fields.

Keywords: Atmosphere stability | DIAL | HYPACT | LIDAR | Plasma shutter | Water vapour

[150] Bellecci C., Martellucci S., Richetta M., Dalu G.A., Aversa P., Casella L., Federico S., Gaudio P., Mobile CO<inf>2</inf> LIDAR/DIAL station, Proceedings of SPIE - The International Society for Optical Engineering, 4070, 59-65, (2000). Abstract
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Abstract: A dial system based on CO2 laser which can be used routinely having an high degrees of eye safety, has been implemented at the Department of Physics of University of Calabria. Starting from this, a mobile dial unit has been realized under the project `LIFE 95/IT/AII/IT/504/CAL' financial support of European Community. We describe the most important, features of the system.

[151] Bellecci C., Gaudio P., Martellucci S., Richetta M., Plasma shutter for CO<inf>2</inf> TEA laser for high range resolved mapping of chemical plume, Proceedings of SPIE - The International Society for Optical Engineering, 3493, 184-189, (1998). Abstract
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Abstract: A plasma shutter has been made for cutting nitrogen tail of energy pulse of TEA CO2 laser. Studies to implement all set-ups has been done using preliminarily a TE CO2 laser source. The system is described and the dependence of the gas break down by energy of the discharge is discussed.

[152] Martellucci S., Bellecci C., Gaudio P., Richetta M., TE-CO<inf>2</inf> injection laser: Status and perspectives, Proceedings of SPIE - The International Society for Optical Engineering, 3433, 165-169, (1998). Abstract
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Abstract: Within the framework of our LIDAR activity 1 devoted to air pollution measurements, we realised the injection of a continuos carbon dioxide laser into a high power TE CO2 laser, to get the possibility of better analyse return signal responses2 and to realise a Doppler wind velocimeter3. Apart from the need of temporally smooth pulse to examine measurements results, in remote sensing it is desirable to use narrow band laser sources. The request of high spectral performances is mainly based on the possibility to use heterodyne detection, on one hand, to improve the signal to noise ratio, and, on the other, to observe and analyse Doppler frequency shift in the return signal. We are engaged in to implement a TE CO2 laser source by injection of a cw pulse from a low pressure CO2. Preliminary results we obtained show a smoothing of the output pulse shape and a consequent reduction in spectral band-width, revealing a single longitudinal mode operation (SLM).

Keywords: Injection | TE-CO 2

[153] Martellucci S., Messina G., Paoletti A., Richetta M., Santangelo S., Spena A., Tebano A., Tucciarone A., Pulsed laser deposition and laser machining of diamond-like carbon films, Proceedings of SPIE - The International Society for Optical Engineering, 3423, 302-308, (1998). Abstract
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Abstract: Recently the application of Pulsed Laser Deposition (PLD) technique to grow different material of relevant interest for applications, especially in the field of micro devices, has been considered We show that thin films of Diamond like Carbon (DLC) can be grown by means of the PLD technique, using an XeCl excimer laser. Their characterisation was carried out by SEM, Raman Spectroscopy and Microindenter. We started a study on the etching mechanism of DLC films for possible applications in microsystems technology.

Keywords: Diamond-like carbon | Laser machining | Pulsed Laser Deposition | Raman Spectroscopy

[154] Martellucci S., Richetta M., Bellecci C., Gaudio P., TE-CO<inf>2</inf> injection laser: status and perspectives, Conference on Lasers and Electro-Optics Europe - Technical Digest, 112, (1998). Abstract
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Abstract: Within the framework of the LIDAR activity, devoted to air pollution measurements, the injection of a continuous carbon dioxide laser into a high power TE-CO2 laser was realized to get the possibility of better analyzed return signal responses and to realize a Doppler wind velocimeter. These results show smoothing of the output pulse shape and a consequent reduction in spectral band-width, revealing single longitudinal mode operation. These evidences were obtained for various values of the injection power level.

[155] Dattoli G., Chiccoli C., Lorenzutta S., Maino G., Richetta M., Torre A., Fourier expansions and multivariable Bessel functions concerning radiation problems, Radiation Physics and Chemistry, 47(2), 183-189, (1996). Abstract
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Abstract: The link between generalized Bessel functions and other special functions is investigated using the Fourier series and the generalized Jacobi-Anger expansion. A new class of multivariable Hermite polynomials is then introduced and their relevance to physical problems discussed. As an example of the power of the method, applied to radiation physics, we analyse the role played by multi-variable Bessel functions in the description of radiation emitted by a charge constrained to a nonlinear oscillation.

[156] Petrocelli G., Martellucci S., Richetta M., Bismuth induced enhancement of the second-harmonic generation efficiency in bismuth-substituted yttrium iron garnet films, Applied Physics Letters, 63(25), 3402-3404, (1993). Abstract
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Abstract: The second-harmonic response of pure and bismuth-substituted yttrium iron garnet films has been measured. A strong enhancement of the second-harmonic generation (SHG) efficiency, related to the incorporation of bismuth, has been observed.

[157] Dattoli G., Chiccoli C., Lorenzutta S., Maino G., Richetta M., Torre A., Advances on the theory of generalized Bessel functions and applications to multiphoton processes, Journal of Scientific Computing, 8(1), 69-109, (1993). Abstract
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Abstract: The generalized Bessel functions (GBF) are presented within the context of a more comprehensive formalism. We also discuss the partial differential equations defining GBF and their modified versions of integer order (MGBF). Numerical results are given for the first-kind MGBF as well as for the GBF with the imaginary parameter, whose importance in multiphoton processes is extensively discussed. © 1993 Plenum Publishing Corporation.

Keywords: electron scattering | Generalized Bessel functions | generating function | multiphotons | sum rules

[158] Dattoli G., Chiccoli C., Lorenzutta S., Maino G., Richetta M., Torre A., Graf-type theorem for Laguerre and Legendre functions, Computers and Mathematics with Applications, 25(12), 99-105, (1993). Abstract
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Abstract: In this paper, we discuss Graf-type series for Laguerre and Legendre functions. Within this context, we indicate the existence of two-variable, one-index generalized functions and discuss their properties. This class of special functions represents a useful tool for dealing with a large number of physical problems, from that relevant to multilevel system dynamics to the study of incommensurate structures. © 1993.

[159] Dattoli G., Gallerano G.P., Mari C., Torre A., Richetta M., Twiss parameters and evolution of quantum harmonic-oscillator states, Il Nuovo Cimento B Series 11, 107(10), 1151-1165, (1992). Abstract
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Abstract: In this paper we show that the evolution of a quantum state, driven by a harmonic-oscillator-type Hamiltonian, can be studied using tools exploited to characterize the evolution of a charged beam in a transport channel. The relevance of the Courrent-Snyder invariant and of Twiss-like parameters to characterize, e.g., the amount of squeezing is carefully pointed out. © 1992 Società Italiana di Fisica.

Keywords: Photon statistics and photon counting

[160] Dattoli G., Galli M., Giannessi L., Ottaviani P.L., Richetta M., Linear undular brightness: Sextupolar magnetic-field contributions and higher-orders energy corrections for low-energy electron beams, Il Nuovo Cimento B Series 11, 107(10), 1135-1142, (1992). Abstract
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Abstract: In this paper we discuss the modifications to the undulator brightness and central wavelength expressions due to the low-energy effects and to the inclusion of the sextupolar magnetic-field components. The corrections are calculated up to the order (K/γ)4. The mathematical details are simplified by the use of generalized Bessel functions. © 1992 Società Italiana di Fisica.

Keywords: Particle beams and particle optics | Particles in electromagnetic fields (including synchrotron radiation)

[161] Dattoli G., Gallerano G.P., Giannessi L., Richetta M., Torre A., Towards a wave theory of charged-beam propagation, Il Nuovo Cimento D, 14(3), 271-278, (1992). Abstract
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Abstract: Using a recent quantum-mechanical treatment of charged-beam propagation in which the emittance plays the role of Planck's constant, we construct a wave theory of the beam transport along guiding systems. We show that the distribution of a beam passing through quadrupole lenses can be described in terms of Gaussian beams. We discuss the role of Twiss parameters within this context and derive an ABCD law for charged beam transport. © 1992 Società Italiana di Fisica.

Keywords: Particles in electromagnetic fields (including synchrotron radiation)

[162] Dattoli G., Mari C., Richetta M., Torre A., On the generalized Twiss parameters and Courant-Snyder invariant in classical and quantum optics, Il Nuovo Cimento B, 107(3), 269-287, (1992). Abstract
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Abstract: In this paper we show how the mathematical tools of the charged-beam transport theory can be applied to classical and quantum optics problems. We discuss the theory of optical-beam transport in fibers, using Twiss parameters and Courant-Snyder invariants. The same quantities are then exploited to discuss the dynamical behaviour of quantum squeezed states. Finally we present generalized Twiss parameters and Courant-Snyder invariants for quadratic Hamiltonians with n degrees of freedom. © 1992 Società Italiana di Fisica.

Keywords: PACS 41.80 Particle beams and particle optics | PACS 42.50.Bs Photon statistics and photon counting

[163] Dattoli G., Giannessi L., Mari C., Richetta M., Torre A., Formal quantum theory of electronic rays, Optics Communications, 87(4), 175-180, (1992). Abstract
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Abstract: A quantum theory of charged beam propagation in transport magnetic structures is developed. The time coordinate of quantum mechanics is replaced by the propagation coordinate and the beam emittance takes the place of Planck's constant. Coherent beam distributions are also discussed. © 1992.

[164] Dattoli G., Fang H., Richetta M., Torre A., Small-signal theory of pulse propagation in free-electron lasers, Physical Review A, 45(6), 4064-4076, (1992). Abstract
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Abstract: We reconsider the theory of pulse propagation in free-electron lasers operating with arbitrary gain. We show that the dynamics can be accounted for by collective longitudinal excitations of supermode type and discuss their properties. We study the interplay between the optical-packet longitudinal dimension and the electron-beam energy spread, along with the induced gain depression. Semianalytical formulas for the gain, pulse length, etc., are presented. © 1992 The American Physical Society.

[165] Dattoli G., Giannessi L., Mari C., Richetta M., Torre A., Linear undulator brightness: Exact analytical treatment, Journal of Mathematical Physics, 33(3), 1200-1207, (1992). Abstract
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Abstract: In this paper it is shown that the calculation of linearly polarized undulator brightness can be worked out exactly using elliptic functions and multivariable generalized Bessel functions. The obtained results are shown to be valid both in nonrelativistic and ultrarelativistic regimes. The physical relevance of the obtained results are discussed and the "low-energy" corrections to the resonance condition are derived. © 1992 American Institute of Physics.

[166] Dattoli G., Chiccoli C., Lorenzutta S., Maino G., Richetta M., Torre A., Generating functions of multivariable generalized Bessel functions and Jacobi-elliptic functions, Journal of Mathematical Physics, 33(1), 25-36, (1992). Abstract
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Abstract: It is pointed out that the Jacobi-elliptic functions are the natural basis to get generating functions of the multivariable generalized Bessel functions. Analytical and numerical results are given of interest for applications. © 1991 American Institute of Physics.

[167] Dattoli G., Giannessi L., Mezi L., Richetta M., Torre A., Linear undulator brightness: Inclusion of sextupolar magnetic-field contributions and of higher-order energy corrections, Physical Review A, 45(6), 4023-4035, (1992). Abstract
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Abstract: In this paper we discuss the theory of emission by relativistic electrons in linearly polarized undulators. We show that the analytical computations are greatly simplified by the introduction of the so-called generalized Bessel functions, originally introduced to treat problems for which the dipolar approximation does not hold. We also discuss the modification induced in the brightness by the inclusion of the sextupolar terms, which arise when electrons are injected off the undulator axis. We show that the phenomonology inherent to this problem is very rich, as additional harmonics come into play and may cause sizable effects. The analysis we develop may be useful to obtain further insight in the physics underlying the so-called inhomogeneously broadened regime. Finally, we also discuss the inclusion of energy corrections up to 1/3 and the relevant physical consequences. © 1992 The American Physical Society.

[168] Dattoli G., Loreto V., Mari C., Richetta M., Torre A., Biunitary transformations and ordinary differential equations.-II, Il Nuovo Cimento B Series 11, 106(12), 1375-1390, (1991). Abstract
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Abstract: We use the results of a recent reformulation of the theory of arbitrary-order differential equations in terms of non-Hermitian operators to show that the invariant binorm is associated to a generalized Courant-Snyder invariant. Furthermore, we indicate the existence of higher-order invariants associated to the Casimir operators of the group, utilized to treat higher-order equations. We also discuss the intrinsic supersymmetric nature of the theory developed. Finally, we show the relevance of the proposed mathematical technique to the design of fiberoptics transport systems. © 1991 Società Italiana di Fisica.

Keywords: Infinite-dimensional Lie groups | Ordinary differential equations | PACS 42.10 | Particle beams and particle optics | Propagation and transmission in homogeneous media

[169] Dattoli G., Loreto V., Mari C., Richetta M., Torre A., Biunitary transformations and ordinary differential equations.-III, Il Nuovo Cimento B Series 11, 106(12), 1391-1399, (1991). Abstract
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Abstract: In two previous papers, the authors have introduced the concept of binormal differential equations. It has been shown that invariants of the Courant-Snyder type are associated to the scalar products of the column vector associated to an ordinary differential equation and to its binormal. In this paper, we show the equivalence of the above invariant and the Lewis form. We also introduce a density matrix for a second-order differential equation and clarify the geometrical meaning of the Twiss parameters. The importance of the above results in the analysis of quantum problems such as, e.g., the evolution of squeezed states is finally stressed. © 1991 Società Italiana di Fisica.

Keywords: Infinite-dimensional Lie groups | Ordinary differential equations | Particle beams and particle optics | Propagation and transmission in homogeneous media

[170] Dattoli G., Loreto V., Mari C., Richetta M., Torre A., Biunitary transformations and ordinary differential equations.-I, Il Nuovo Cimento B Series 11, 106(12), 1357-1374, (1991). Abstract
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Abstract: We reformulate the theory of ordinary differential equations of arbitrary order with nonconstant coefficients, using the formalism of non-Hermitian operators. In particular, exploiting the technique of dissipative quantum mechanics, we show that the solution of the equations can be written in terms of a nonunitary evolution operator. Furthermore, we point out that the solution of the adjoint equations can be derived from an associated biunitary operator. We show that a number of invariants, not previously discussed, exhists. Finally, we prove that the method allows the search for approximate solutions that can be used in many physical problems. © 1991 Società Italiana di Fisica.

Keywords: Infinite-dimensional Lie groups | Ordinary differential equations | Particle beams and particle optics | Propagation and transmission in homogeneous media

[171] Dattoli G., Chiccoli C., Lorenzutta S., Maino G., Richetta M., Torre A., A note on the theory of n-variable generalized bessel functions, Il Nuovo Cimento B Series 11, 106(10), 1159-1166, (1991). Abstract
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Abstract: In this note we introduce a further generalization of Bessel-type functions, discussing the case of a multivariables and one-index function. This kind of function can be usefully exploited in problems in which the dipole approximation does not hold and many higher harmonics are simultaneously operating. We analyse the relevant recurrence properties, the modified forms and the generating functions. © 1991 Società Italiana di Fisica.

Keywords: PACS 02.30.Gp Special functions

[172] Dattoli G., Giubileo C., Mezi L., Richetta M., Ronsivalle C., Torre A., A perturbative analysis of the Kapchinskij-Vladimirskij problem in the emittance-dominanted regime, Il Nuovo Cimento B, 106(6), 697-700, (1991). Abstract
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Abstract: In this paper we present a first-order perturbative analysis of the space-charge effect on a charged beam with cylindrical symmetry. In particular we discuss the modification induced in the propagation through a drift space and a thin lens. © 1991 Società Italiana di Fisica.

Keywords: 41.80 - Particle beams and particle optics

[173] Dattoli G., Torre A., Fang H., Gallardo J.C., Richetta M., The 3-D FEL pulse propagation equation: An analytical treatment in the low-gain and small-signal regime, Il Nuovo Cimento D, 13(5), 615-632, (1991). Abstract
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Abstract: In this paper we show that the transverse mode evolution of a FEL operating with short pulses can be treated, in the small-signal and low-gain regime, using a relatively simple mathematical technique leading to a potentially fast numerical algorithm. We also point out that analytical solutions can be obtained for the cases where the slippage length is small compared to the longitudinal bunch length. © 1991 Società Italiana di Fisica.

Keywords: amplifiers | cavities | Laser beam deflection and focusing | Laser resonators

[174] Dattoli G., Fang H., Gallardo J.C., Richetta M., Torre A., A simple treatment of the FEL pulse-propagation problem with the inclusion of transverse-mode dynamics, Nuclear Inst. and Methods in Physics Research, A, 296(1-3), 322-334, (1990). Abstract
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Abstract: In this paper we discuss a simple mathematical method to solve the Colson wave equation in the small-signal regime and include transverse- and longitudinal-mode dynamics. © 1990.

[175] Dattoli G., Giannessi L., Hermsen T., Renieri A., Richetta M., Torre A., FEL gain in the pulsed regime: a comparison between numerical and analytical results, Il Nuovo Cimento D, 12(1), 21-34, (1990). Abstract
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Abstract: In this paper we present simple and general formulae for the FEL gain in the pulsed regime including both the longitudinal mode coupling and the lethargy effect. Such relations, obtained from a numerical integration of the pulse propagation equations, are then compared to similar expressions obtained analitycally in the limiting case of the long bunch approximation and the agreement is shown to be excellent. © 1990 Societá Italiana di Fisica.

Keywords: Photoelectric and optoelectronic devices and systems

[176] Dattoli G., Richetta M., Schettini G., Torre A., Lie algebraic methods and solutions of linear partial differential equations, Journal of Mathematical Physics, 31(12), 2856-2863, (1990). Abstract
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Abstract: In this paper, an algebraic method to obtain the solution of linear partial differential equations of the evolution type is discussed. The proposed method exploits the Lie differential operators and their matrix realization, to reduce the equation to an easily solvable generalized matrix form. Some applications to problems of specific interest are also discussed. © 1990 American Institute of Physics.

[177] Dattoli G., Fang H., Giannessi L., Richetta M., Torre A., Caloi R., Parametrizing the gain dependences in a single passage FEL operating with moderate current e-beams, Nuclear Inst. and Methods in Physics Research, A, 285(1-2), 108-114, (1989). Abstract
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Abstract: In this paper we analyze an FEL operating in the moderate gain regime (0 < g0 < 10) and discuss the modification induced on the well-known antisymmetric gain formula by nonlinear contributions in the gain coefficient. The gain degradations due to e-beam energy spread and emittances are also included, as well as those due to finite electron pulse effects. Final comments on the attainable laser pulse length and bandwidth are also presented. © 1989.

[178] Dattoli G., Richetta M., Torre A., The Cayley-Klein parameters and geometrical picture of the multilevel system evolution, Il Nuovo Cimento B Series 11, 104(6), 665-683, (1989). Abstract
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Abstract: In this paper we complete the study of the evolution of multilevel systems in terms of a geometrical picture based on the so-called Cayley-Klein parameters introduced to describe rotations in classical mechanics. It is shown that these parameters and their identification in terms of Euler angles are helpful and insightful tools to clarify the dynamical features of two- and three-level atoms interacting with intense external radiation. It is finally shown that the evolution of, e.g., the three-level case depends on a rotation matrix fully equivalent to the Kobayashi-Maskawa matrix introduced in elementary-particle theory to account for generalized Cabibbo mixing angles and CP-violations in weak-decay processes. © 1989 Società Italiana di Fisica.

Keywords: PACS 03.65.Fd Algebraic methods | PACS 11.30.Jw SU and SU symmetries 2 3 | PACS 12.30 Models of weak interactions

[179] Dattoli G., Giannessi L., Richetta M., Torre A., NYekOtORyYe RYezhUl{cyrillic small soft sign}tAt y, sV{cyrillic small soft sign}zhANNyYe s BYeskONYe ChNyMI R{cyrillic small soft sign}DAMI BYessYelYeVykh FU NktsII, Il Nuovo Cimento, 103(2), 149-159, (1989). Abstract
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Abstract: In this paper we discuss an approach to infinite series of Bessel functions, exploiting a method based on a combination of the integral representation and the generating function technique. We also present a connection between Newberger type series and the Anger function. © 1989 Società Italiana di Fisica.

Keywords: 02.30 | analysis | Function theory

[180] Dattoli G., Torre A., Centioli C., Richetta M., Free-Electron Laser Operation in the Intermediate Gain Region, IEEE Journal of Quantum Electronics, 25(11), 2327-2331, (1989). Abstract
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Abstract: In this paper, we explore the modification induced on the welLKnown antisymmetric gain function of FEL when the gain coefficient g0 ranges up to 10. We point out that deviations from the linear regime are present for g0 ≥ 0.5, and also discuss a simple perturbative analysis, which accounts remarkably well for the corrections to the linear gain formula even for g0 = 10. The effect of inhomogeneous broadening is also discussed. © 1989 IEEE

[181] Dattoli G., Torre A., Reali G., Richetta M., Supermode biorthogonality in free-electron lasers: A physical interpretation, Il Nuovo Cimento B Series 11, 101(5), 585-593, (1988). Abstract
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Abstract: The eigenmodes of the longitudinal pulse propagation equation of free-electron lasers (FEL) are not in general orthogonal to each other, but rather biorthogonal to an adjoint set of eigenmodes which, we will show, represent the FEL propagation in thé reverse direction in the same resonator. We also point out the analogies of the present analysis with that relevant to the transverse-mode evolution in conventional lasers. © 1988 Società Italiana di Fisica.

Keywords: 42.60.He | Optical problems related to properties and interactions of laser beams

[182] Dattoli G., Richetta M., Torre A., Evolution of SU(2) and SU(1,1) states: A further mathematical analysis, Journal of Mathematical Physics, 29(12), 2586-2588, (1988). Abstract
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Abstract: The problem of the evolution of SU(2) and SU(1,1) states is analyzed from a unified point of view. A generalized Rabi matrix for a time-dependent SU(2)-SU(1,1) coherence preserving Hamiltonian is also derived. © 1988 American Institute of Physics.

[183] Dattoli G., Richetta M., Torre A., Operator disentanglement, Physical Review A, 37(6), 2007-2011, (1988). Abstract
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Abstract: We obtain the time-ordered form of the evolution operator for Hamiltonian linear combinations of the generators of the SU(1,1), SU(2), and h(4) groups. The relevance of the obtained results to physics problems such as the generation of non-Poissonian statistics in laser-plasma scattering and the pulse propagation in free-electron lasers is also briefly discussed. © 1988 The American Physical Society.

[184] Dattoli G., Gallardo J.C., Renieri A., Richetta M., Torre A., Quantum coherence properties of the FEL, Nuclear Inst. and Methods in Physics Research, A, 237(1-2), 93-99, (1985). Abstract
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Abstract: In this paper we discuss the quantum coherence properties of the FEL within the framework of the single electron non-relativistic Hamiltonian picture. We analyse both single and multimode problems. © 1985.

[185] Dattoli G., Gallardo J., Renieri A., Richetta M., QUANTUM STATISTICAL PROPERTIES OF AN FEL AMPLIFIER., IEEE Journal of Quantum Electronics, QE-21(7), 1069-1072, (1985). Abstract
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Abstract: We discuss the problem of photon quantum statistics of a single particle free-electron laser (FEL) amplifier in the small-signal cold beam regime to first order in the electron quantum recoil. The initial radiation wave is an arbitrary coherent state. We show that Glauber coherence is not preserved by the FEL interaction if the initial coherent state is not the vacuum, even if we neglect the electron quantum recoil (absence of gain). We evaluate the first two moments of the final photon distribution and find sub- (super)-Poissonian photon statistics for a negative (positive) resonance parameter.

[186] Bosco P., Dattoli G., Richetta M., Comments on the solution of the spherical Raman-Nath equation, Journal of Physics A: General Physics, 17(7), (1984). Abstract
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Abstract: The authors present a preliminary investigation of the spherical Raman- Nath equation, and discuss the connections between its solution and previously known cases.

[187] Dattoli G., Richetta M., Pinto I., Recursive differential equations of the raman-nath type: A general review, Il Nuovo Cimento D, 4(3), 293-311, (1984). Abstract
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Abstract: In this paper we discuss the differential recursive equations of the Raman-Nath type and introduce a very general technique of analysis, valid for both exact and perturbed solutions. © 1984 Società Italiana di Fisica.

Keywords: Nonlinear optics

[188] Dattoli G., Richetta M., FEL quantum theory: Comments on Glauber coherence, antibunching and squeezing, Optics Communications, 50(3), 165-168, (1984). Abstract
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Abstract: The problem of the FEL statistics is reconsidered, we show that Glauber coherence is not preserved in the FEL operation and that, in principle, antibunching and squeezed states may be generated. © 1984.

[189] Ciocci F., Dattoli G., Richetta M., Analysis of the harmonic Raman-Nath equation, Journal of Physics A: Mathematical and General, 17(6), 1333-1342, (1984). Abstract
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Abstract: Analyses the Harmonic Raman-Nath equation and present a non-trivial perturbative solution. The connection with the conventional Raman-Nath equation is also discussed. © 1984 IOP Publishing Ltd.

[190] Dattoli G., Renieri A., Richetta M., QUANTUM FREE ELECTRON LASER STATISTIC: A CRITICAL REVIEW., AIP Conference Proceedings, 125-130, (1984). Abstract
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Abstract: The main aspects of the up to now developed quantum FEL theories are reviewed and it is emphasized that, under proper conditions, FEL may be an interesting device to observe some genuine quantum effects as antibunching and squeezing.