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C. Porosnicu
Atomistilor, National Institute for Laser Plasma and Radiation Physics, Magurele, Ilfov, ROMANIA

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Accepted manuscript
Published: 14 April 2020 in Journal of Physics D: Applied Physics
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Deuterium retention and release behavior were investigated in this study, for thin layers of beryllium, tungsten and mixed beryllium/tungsten layers which are of concern for next-generation thermonuclear fusion devices like International Thermonuclear Experimental Reactor. The layers were resulted from deposition with Thermionic Vacuum Arc technology by using two different ion acceleration voltages 0 V and -700 V respectively and were subsequently implanted by exposure to a steady-state deuterium plasma with ion energies of 240 eV/D for D3 and 360 eV/D for D2 at a specific fluency of 2.85×1020 m-2 *s. Morphology studies indicate that it is strongly influenced by layer composition and by the ion acceleration voltage applied in-situ during layer deposition. Structural analysis shows the presence of a polycrystalline W metallic phase and also highlights a dependence between tungsten crystallite size and Be/W atomic ratio. Thermal desorption spectra show that the nature of deuterium trapping states in layers are significantly affected by the beryllium/tungsten ratio and deposition conditions. On the other hand, the amount of deuterium in mixed layers is lower than in pure beryllium layers indicating that W is mitigating D binding states. Also, layers deposited with -700 V show a decreased retention compared to their counterparts deposited at 0 V, indicating that retention in ITER will be influenced by re-deposited layers properties such as microstructure and compactness.

ACS Style

Paul Dinca; Bogdan Butoi; Corneliu Porosnicu; Gloria Oana Pompilian; Cornel Staicu; Cristian P Lungu; Ion Burducea. Structure, morphology and deuterium retention and release properties of pure and mixed Be and W layers. Journal of Physics D: Applied Physics 2020, 53, 325304 .

AMA Style

Paul Dinca, Bogdan Butoi, Corneliu Porosnicu, Gloria Oana Pompilian, Cornel Staicu, Cristian P Lungu, Ion Burducea. Structure, morphology and deuterium retention and release properties of pure and mixed Be and W layers. Journal of Physics D: Applied Physics. 2020; 53 (32):325304.

Chicago/Turabian Style

Paul Dinca; Bogdan Butoi; Corneliu Porosnicu; Gloria Oana Pompilian; Cornel Staicu; Cristian P Lungu; Ion Burducea. 2020. "Structure, morphology and deuterium retention and release properties of pure and mixed Be and W layers." Journal of Physics D: Applied Physics 53, no. 32: 325304.

Journal article
Published: 28 March 2020 in Coatings
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Autonomous smart natural ventilation systems (SVS) attached to the glass façade of living quarters and office buildings can help reducing the carbon footprint of city buildings in the future, especially during warm seasons and can represent an alternative to the conventional mechanical ventilation systems. The work performed in this manuscript focuses on the investigation of bacteria trapping and killing efficiency of stainless steel grids coated with a mixed layer of Cu-Ag. These grids are to be employed as decontamination filters for a smart natural ventilation prototype that we are currently building in our laboratory. The tested grids were coated with a mixed Cu-Ag layer using thermionic vacuum arc plasma processing technology. The fixed deposition geometry allowed the variation of Cu and Ag atomic concentration in coated layers as a function of substrate position in relation to plasma sources. The test conducted with air contaminated with a pathogen strain of staphylococcus aureus indicated that the filtering efficiency is influenced by two parameters: the pore size dimension and the coating layer composition. The results show that the highest filtering efficiency of 100% was obtained for fine pore (0.5 × 0.5 mm) grids coated with a mixed metallic layer composed of 65 at% Cu and 35 at% Ag. The second test performed only on reference grids and Cu-Ag (65–35 at%) under working conditions, confirm a similar filtering efficiency for the relevant microbiological markers. This particular sample was investigated from morphological, structural, and compositional point of view. The results show that the layer has a high surface roughness with good wear resistance and adhesion to the substrate. The depth profiles presented a uniform composition of Cu and Ag in the layer with small variations caused by changes in deposition rates during the coating process. Identification of the two metallic phases of the Cu and Ag in the layers evidences their crystalline nature. The calculated grain size of the nanocrystalline was in the range 14–21 nm.

ACS Style

P. Dinca; B. Butoi; M. Lungu; C. Porosnicu; I. Jepu; C. Staicu; C.P. Lungu; A. Niculescu; I. Burducea; O. Trusca; M. Diaconu; I. Cretescu; G. Soreanu. Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method. Coatings 2020, 10, 322 .

AMA Style

P. Dinca, B. Butoi, M. Lungu, C. Porosnicu, I. Jepu, C. Staicu, C.P. Lungu, A. Niculescu, I. Burducea, O. Trusca, M. Diaconu, I. Cretescu, G. Soreanu. Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method. Coatings. 2020; 10 (4):322.

Chicago/Turabian Style

P. Dinca; B. Butoi; M. Lungu; C. Porosnicu; I. Jepu; C. Staicu; C.P. Lungu; A. Niculescu; I. Burducea; O. Trusca; M. Diaconu; I. Cretescu; G. Soreanu. 2020. "Antibacterial Efficiency of Stainless-Steel Grids Coated with Cu-Ag by Thermionic Vacuum Arc Method." Coatings 10, no. 4: 322.

Accepted manuscript
Published: 17 January 2020 in Physica Scripta
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C-Ti multilayer nanostructures were deposed by Thermionic Vacuum Arc (TVA) technology. The layers consisting of about 100nm Carbon base layer and seven 40nm alternatively Ti and C layers were deposed on Silicon substrates. On the other hand, in order to obtain C-Ti multilayer structures with variable thickness and different percentages in C and Ti of layers, a 20nm thick C layer was first deposed on Si substrate and then seven Ti-C layers, each of these having thickness of up to 40nm were deposed. To perform the successively layers with various thickness were changed the discharge parameters for C and Ti plasma sources to obtain the desirable thickness. By changing of substrate temperature between room temperature and 300°C and on the other hand the bias voltage up to -700V, different batches of samples were obtained for this study. To characterize properties of as prepared C-Ti multilayer structures were used Electron Microscopy techniques (TEM, STEM), Raman Spectroscopy, RBS techniques and tribological measurements. To characterize the electrical conductive properties, the electrical surface resistance versus temperature have been measured, and then the electrical conductivity. Using the Wiedemann-Frantz law was calculated the thermal conductivity.

ACS Style

Victor Ciupina; Cristian P Lungu; Rodica Vladoiu; Corneliu Porosnicu; Eugeniu Vasile; Virginia Nicolescu; Aurelia Mandes; Virginia Dinca-Balan; Ovidiu Cupsa. Carbon–titanium nanostructures: synthesis and characterization. Physica Scripta 2020, 95, 044012 .

AMA Style

Victor Ciupina, Cristian P Lungu, Rodica Vladoiu, Corneliu Porosnicu, Eugeniu Vasile, Virginia Nicolescu, Aurelia Mandes, Virginia Dinca-Balan, Ovidiu Cupsa. Carbon–titanium nanostructures: synthesis and characterization. Physica Scripta. 2020; 95 (4):044012.

Chicago/Turabian Style

Victor Ciupina; Cristian P Lungu; Rodica Vladoiu; Corneliu Porosnicu; Eugeniu Vasile; Virginia Nicolescu; Aurelia Mandes; Virginia Dinca-Balan; Ovidiu Cupsa. 2020. "Carbon–titanium nanostructures: synthesis and characterization." Physica Scripta 95, no. 4: 044012.

Journal article
Published: 01 January 2020 in Physica Scripta
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ACS Style

Miroslaw Zlobinski; G De Temmerman; C Porosnicu; D Matveev; B Unterberg; G Sergienko; S Brezinsek; D Nicolai; A Terra; M Rasinski; B Spilker; M Freisinger; S Möller; Ch Linsmeier; C P Lungu; P Dinca. Efficiency of laser-induced desorption of D from Be/D layers and surface modifications due to LID. Physica Scripta 2020, T171, 014075 .

AMA Style

Miroslaw Zlobinski, G De Temmerman, C Porosnicu, D Matveev, B Unterberg, G Sergienko, S Brezinsek, D Nicolai, A Terra, M Rasinski, B Spilker, M Freisinger, S Möller, Ch Linsmeier, C P Lungu, P Dinca. Efficiency of laser-induced desorption of D from Be/D layers and surface modifications due to LID. Physica Scripta. 2020; T171 ():014075.

Chicago/Turabian Style

Miroslaw Zlobinski; G De Temmerman; C Porosnicu; D Matveev; B Unterberg; G Sergienko; S Brezinsek; D Nicolai; A Terra; M Rasinski; B Spilker; M Freisinger; S Möller; Ch Linsmeier; C P Lungu; P Dinca. 2020. "Efficiency of laser-induced desorption of D from Be/D layers and surface modifications due to LID." Physica Scripta T171, no. : 014075.

Journal article
Published: 01 January 2020 in Physica Scripta
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ACS Style

Antti Hakola; Kalle Heinola; Kenichiro Mizohata; Jari Likonen; Cristian Lungu; Corneliu Porosnicu; Eduardo Alves; Rodrigo Mateus; Iva Bogdanovic Radovic; Zdravko Siketic; Vincenc Nemanic; Mohit Kumar; Cedric Pardanaud; Pascale Roubin; Eurofusion Wp Pfc Contributors. Effect of composition and surface characteristics on fuel retention in beryllium-containing co-deposited layers. Physica Scripta 2020, T171, 014038 .

AMA Style

Antti Hakola, Kalle Heinola, Kenichiro Mizohata, Jari Likonen, Cristian Lungu, Corneliu Porosnicu, Eduardo Alves, Rodrigo Mateus, Iva Bogdanovic Radovic, Zdravko Siketic, Vincenc Nemanic, Mohit Kumar, Cedric Pardanaud, Pascale Roubin, Eurofusion Wp Pfc Contributors. Effect of composition and surface characteristics on fuel retention in beryllium-containing co-deposited layers. Physica Scripta. 2020; T171 ():014038.

Chicago/Turabian Style

Antti Hakola; Kalle Heinola; Kenichiro Mizohata; Jari Likonen; Cristian Lungu; Corneliu Porosnicu; Eduardo Alves; Rodrigo Mateus; Iva Bogdanovic Radovic; Zdravko Siketic; Vincenc Nemanic; Mohit Kumar; Cedric Pardanaud; Pascale Roubin; Eurofusion Wp Pfc Contributors. 2020. "Effect of composition and surface characteristics on fuel retention in beryllium-containing co-deposited layers." Physica Scripta T171, no. : 014038.

Journal article
Published: 01 January 2020 in Physica Scripta
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ACS Style

P Veis; A Marín-Roldán; V Dwivedi; J Karhunen; P Paris; I Jõgi; C Porosnicu; C P Lungu; V Nemanic; A Hakola. Quantification of H/D content in Be/W mixtures coatings by CF-LIBS. Physica Scripta 2020, T171, 014073 .

AMA Style

P Veis, A Marín-Roldán, V Dwivedi, J Karhunen, P Paris, I Jõgi, C Porosnicu, C P Lungu, V Nemanic, A Hakola. Quantification of H/D content in Be/W mixtures coatings by CF-LIBS. Physica Scripta. 2020; T171 ():014073.

Chicago/Turabian Style

P Veis; A Marín-Roldán; V Dwivedi; J Karhunen; P Paris; I Jõgi; C Porosnicu; C P Lungu; V Nemanic; A Hakola. 2020. "Quantification of H/D content in Be/W mixtures coatings by CF-LIBS." Physica Scripta T171, no. : 014073.

Journal article
Published: 06 December 2019 in Materials
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Reduced activation ferritic and martensitic steel like EUROFER (9Cr-1W) are considered as potential structural materials for the first wall of the future next-generation DEMOnstration Power Station (DEMO) fusion reactor and as a reference material for the International Thermonuclear Experimental Reactor (ITER) test blanket module. The primary motivation of this work is to study the re-deposition of the main constituent materials of EUROFER, namely tungsten (W), iron (Fe), and chromium (Cr), in a DEMO type reactor by producing and analyzing complex WxCryFe1−x−y layers. The composite layers were produced in laboratory using the thermionic vacuum arc (TVA) method, and the morphology, crystalline structure, elemental composition, and mechanical properties were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-X-ray fluorescence (micro-XRF), and glow discharge optical emission spectrometry (GDOES), as well as nanoindentation and tribology measurements. The results show that the layer morphology is textured and is highly dependent on sample positioning during the deposition process. The formation of polycrystalline WxCryFe1−x−y was observed for all samples with the exception of the sample positioned closer to Fe anode during deposition. The crystalline grain size dimension varied between 10 and 20 nm. The composition and thickness of the layers were strongly influenced by the in-situ coating position, and the elemental depth profiles show a non-uniform distribution of Fe and Cr in the layers. The highest hardness was measured for the sample positioned near the Cr anode, 6.84 GPa, and the lowest was 4.84 GPa, measured for the sample positioned near the W anode. The tribology measurements showed an abrasive sliding wear behavior for most of the samples with a reduction of the friction coefficient with the increase of the normal load.

ACS Style

Mihail Lungu; Ioana Porosnicu; Paul Dinca; Alin Velea; Flaviu Baiasu; Bogdan Butoi; Oana Gloria Pompilian; Cornel Staicu; Parau Anca Constantina; Corneliu Porosnicu; Cristian Lungu; Ion Tiseanu. Structural, Compositional, and Mechanical Characterization of WxCryFe1−x−y Layers Relevant to Nuclear Fusion, Obtained with TVA Technology. Materials 2019, 12, 4072 .

AMA Style

Mihail Lungu, Ioana Porosnicu, Paul Dinca, Alin Velea, Flaviu Baiasu, Bogdan Butoi, Oana Gloria Pompilian, Cornel Staicu, Parau Anca Constantina, Corneliu Porosnicu, Cristian Lungu, Ion Tiseanu. Structural, Compositional, and Mechanical Characterization of WxCryFe1−x−y Layers Relevant to Nuclear Fusion, Obtained with TVA Technology. Materials. 2019; 12 (24):4072.

Chicago/Turabian Style

Mihail Lungu; Ioana Porosnicu; Paul Dinca; Alin Velea; Flaviu Baiasu; Bogdan Butoi; Oana Gloria Pompilian; Cornel Staicu; Parau Anca Constantina; Corneliu Porosnicu; Cristian Lungu; Ion Tiseanu. 2019. "Structural, Compositional, and Mechanical Characterization of WxCryFe1−x−y Layers Relevant to Nuclear Fusion, Obtained with TVA Technology." Materials 12, no. 24: 4072.

Journal article
Published: 06 November 2019 in Fusion Engineering and Design
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Since the largest area of the JET first wall is composed of beryllium, it is expected that nuclear fuel is largely retained in beryllium-based co-deposits with low amounts of carbon. Co-deposited layers obtained in the laboratory, with similar stoichiometry with the ones found in JET ITER-like wall (ILW) experiments, can provide complementary information regarding the hydrogen isotopes inventory and release behaviour. We report on the analysis of the beryllium-based layers deposited by the direct current magnetron sputtering method on pure tungsten and silicon substrates. The thickness of studied layers with various amounts of deuterium, oxygen, and carbon was between 2 and 7 μm. Samples from the same batch were distributed to different laboratories and characterised by various analytical methods. Scanning electron microscopy was applied to determine the exact thickness, data from elastic backscattering spectrometry and nuclear reaction analysis to profile the depth content of light elemental species as deuterium, and thermal desorption spectroscopy to quantify the amount of deuterium and also to observe release kinetics. The main finding is that a high amount of deuterium, from 8 at.% up to 28 at.%, can be retained in the films. Deuterium release at a heating rate of 0.125 °C/s reached its maximum intensity at peaks of various widths and shape, which appeared at temperatures from 340 °C up to 660 °C, depending on the thickness, the layer stoichiometry and deposition parameters.

ACS Style

V. Nemanič; M. Žumer; C. Porosnicu; B. Butoi; E. Alves; R. Mateus. Deuterium inventory determination in beryllium and mixed beryllium-carbon layers doped with oxygen. Fusion Engineering and Design 2019, 150, 111365 .

AMA Style

V. Nemanič, M. Žumer, C. Porosnicu, B. Butoi, E. Alves, R. Mateus. Deuterium inventory determination in beryllium and mixed beryllium-carbon layers doped with oxygen. Fusion Engineering and Design. 2019; 150 ():111365.

Chicago/Turabian Style

V. Nemanič; M. Žumer; C. Porosnicu; B. Butoi; E. Alves; R. Mateus. 2019. "Deuterium inventory determination in beryllium and mixed beryllium-carbon layers doped with oxygen." Fusion Engineering and Design 150, no. : 111365.

Accepted manuscript
Published: 09 May 2019 in Nuclear Fusion
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Data on erosion and melting of beryllium upper limiter tiles, so-called dump plates (DP), are presented for all three campaigns in the JET tokamak with the ITER-like wall. High-resolution images of the upper wall of JET, show clear signs of flash melting on the ridge of the roof-shaped tiles. The melt layers move in the poloidal direction from the inboard to the outboard tile ending on the last DP tile with an upward going waterfall-like melt structure. Melting was caused mainly by unmitigated plasma disruptions. During three ILW campaigns around 15% of all 12376 plasma pulses were catalogued as disruptions. Thermocouple data from the upper dump plates tiles showed a reduction in energy delivered by disruptions with fewer extreme events in the third campaign, ILW-3, in comparison to ILW-1 and ILW-2. The total Be erosion assessed via precision weighing of tiles retrieved from JET during shutdowns indicated the increasing mass loss across campaigns of up to 0.6 g from a single tile. The mass of splashed melted Be on the upper walls was also estimated using the high-resolution images of wall components taken after each campaign. The results agree with the total material loss estimated by tile weighing (~130 g). Morphological and structural analysis performed on Be melt layers revealed a multilayer structure of re-solidified material composed mainly of Be and BeO with some heavy metal impurities Ni, Fe, W. IBA analysis performed across the affected tile ridge in both poloidal and toroidal direction revealed a low D concentration, in the range 1 – 4 x 1017 D atoms/cm2.

ACS Style

Ionut Jepu; G.F. Matthews; Anna Widdowson; Marek Rubel; Elzbieta Fortuna-Zalesna; Joanna Zdunek; Per Petersson; Vaughan K Thompson; Paul Dinca; Corneliu Porosnicu; Paul Coad; Kalle Heinola; Norberto Catarino; O.G. Pompilian; Cristian P Lungu; Jet Contributors. Beryllium melting and erosion on the upper dump plates in JET during three ITER-like wall campaigns. Nuclear Fusion 2019, 59, 086009 .

AMA Style

Ionut Jepu, G.F. Matthews, Anna Widdowson, Marek Rubel, Elzbieta Fortuna-Zalesna, Joanna Zdunek, Per Petersson, Vaughan K Thompson, Paul Dinca, Corneliu Porosnicu, Paul Coad, Kalle Heinola, Norberto Catarino, O.G. Pompilian, Cristian P Lungu, Jet Contributors. Beryllium melting and erosion on the upper dump plates in JET during three ITER-like wall campaigns. Nuclear Fusion. 2019; 59 (8):086009.

Chicago/Turabian Style

Ionut Jepu; G.F. Matthews; Anna Widdowson; Marek Rubel; Elzbieta Fortuna-Zalesna; Joanna Zdunek; Per Petersson; Vaughan K Thompson; Paul Dinca; Corneliu Porosnicu; Paul Coad; Kalle Heinola; Norberto Catarino; O.G. Pompilian; Cristian P Lungu; Jet Contributors. 2019. "Beryllium melting and erosion on the upper dump plates in JET during three ITER-like wall campaigns." Nuclear Fusion 59, no. 8: 086009.

Journal article
Published: 12 March 2019 in Applied Surface Science
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The aim of this paper is to investigate the influence of the thermionic vacuum arc (TVA) operation parameters (arc current, arc voltage and thermo-emission filament current) on the Be ion energy and plasma ionization degree, as well as on the topological, structural and mechanical properties of Be thin films. For this purpose, nanocrystalline Be thin films, with thickness of approximately 1 μm, were deposited by TVA on not intentionally heated silicon and stainless steel substrates by varying the arc voltage from 0.8 to 2.0 kV. Topological, structural and mechanical (hardness, Young's modulus, adhesion critical loads, and friction coefficient) properties of Be thin films were investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), nanoindentation and scratch tests. The mechanical behaviour and structural changes are discussed based on TVA plasma diagnostics results. Be ion energy and plasma ionization degree were measured using cold and emissive probes, energy-resolved mass spectrometer and a quartz crystal microbalance. The preferential crystallographic orientation, morphology and packing density are sensitive to the selected processing parameters which, in turn, control, over a wide range, the plasma ionization degree and Be ion energy. The film deposited using an arc voltage value of 1.5 kV exhibits dense structure with low lattice defect density, high hardness, low coefficient of friction, good wear-resistance, fracture toughness and adhesion to the substrate.

ACS Style

Vasile Tiron; Corneliu Porosnicu; Paul Dinca; Ioana-Laura Velicu; Daniel Cristea; Daniel Munteanu; Ádám Révész; George Stoian; Cristian P. Lungu. Beryllium thin films deposited by thermionic vacuum arc for nuclear applications. Applied Surface Science 2019, 481, 327 -336.

AMA Style

Vasile Tiron, Corneliu Porosnicu, Paul Dinca, Ioana-Laura Velicu, Daniel Cristea, Daniel Munteanu, Ádám Révész, George Stoian, Cristian P. Lungu. Beryllium thin films deposited by thermionic vacuum arc for nuclear applications. Applied Surface Science. 2019; 481 ():327-336.

Chicago/Turabian Style

Vasile Tiron; Corneliu Porosnicu; Paul Dinca; Ioana-Laura Velicu; Daniel Cristea; Daniel Munteanu; Ádám Révész; George Stoian; Cristian P. Lungu. 2019. "Beryllium thin films deposited by thermionic vacuum arc for nuclear applications." Applied Surface Science 481, no. : 327-336.

Journal article
Published: 08 February 2019 in Surface and Coatings Technology
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Co-sputtering of tungsten‑aluminum fusion relevant materials in a dual-High Power Impulse Magnetron Sputtering discharge, operated in different Ar-D2 gas mixtures, was investigated in gas phase by means of energy-resolving mass spectrometry. Experimental results indicate that the total ion flux and its composition are strongly dependent on sputtering gas composition and the average power applied to the targets. During single HiPIMS operation with W target, the D− ions are the most abundant species. The measured D− ion flux shows an increase with the rising of D2 content in Ar-D2 gas mixture and a linear increase with the power applied to the W target. In contrast, during dual-HiPIMS operation, a decrease of D− ion flux was observed when the input power applied to the Al target was increased. The origin of different deuterium ion species and retention mechanisms are discussed. The surface morphology, microstructure and chemical composition of the W-Al coatings obtained in Ar-D2, were investigated by means of, Atomic Force Microscopy, X-ray diffraction and Glow Discharge Optical Emission Spectroscopy. GDOES depth profiles show the presence of a large amount of deuterium (up to 21 at.%) in the mixed W-Al layers and indicate that the D retention in the mixed W-Al layers is mainly related to the W in-depth concentration and less dependent on the Al one. The intense and energetic bombardment of the growing film with D− ions seems to be responsible for the large amount of D retained in the W-Al layers.

ACS Style

P. Dinca; V. Tiron; I.-L. Velicu; C. Porosnicu; B. Butoi; Alin Velea; E. Grigore; Claudiu Costin; C.P. Lungu. Negative ion-induced deuterium retention in mixed W-Al layers co-deposited in dual-HiPIMS. Surface and Coatings Technology 2019, 363, 273 -281.

AMA Style

P. Dinca, V. Tiron, I.-L. Velicu, C. Porosnicu, B. Butoi, Alin Velea, E. Grigore, Claudiu Costin, C.P. Lungu. Negative ion-induced deuterium retention in mixed W-Al layers co-deposited in dual-HiPIMS. Surface and Coatings Technology. 2019; 363 ():273-281.

Chicago/Turabian Style

P. Dinca; V. Tiron; I.-L. Velicu; C. Porosnicu; B. Butoi; Alin Velea; E. Grigore; Claudiu Costin; C.P. Lungu. 2019. "Negative ion-induced deuterium retention in mixed W-Al layers co-deposited in dual-HiPIMS." Surface and Coatings Technology 363, no. : 273-281.

Journal article
Published: 04 January 2019 in Fusion Engineering and Design
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Chemical reactions involving co-deposits in plasma facing components will occur under heat loads. Previous experiments in the Be-C-O system evidenced that compound formation may induce by itself the peel-off of deposits when C films are annealed in vacuum due to the simultaneous formation and mixing of Be2C and BeO. The present experiment investigates the reverse case, where Be films are deposited on graphite and annealed up to 1073 K. The delamination mechanism also exist and it is initialise at 973 K. However, it remains scarce since the carbide and oxide phases grow preferentially at different depths. The experiment points C as a source of dust in presence of Be in operative scenarious. Phase formation was followed by ion beam analysis, X-ray diffraction and electron microscopy.

ACS Style

R. Mateus; C. Porosnicu; N. Franco; P.A. Carvalho; C.P. Lungu; E. Alves. Stability of beryllium coatings deposited on carbon under annealing up to 1073 K. Fusion Engineering and Design 2019, 146, 303 -307.

AMA Style

R. Mateus, C. Porosnicu, N. Franco, P.A. Carvalho, C.P. Lungu, E. Alves. Stability of beryllium coatings deposited on carbon under annealing up to 1073 K. Fusion Engineering and Design. 2019; 146 ():303-307.

Chicago/Turabian Style

R. Mateus; C. Porosnicu; N. Franco; P.A. Carvalho; C.P. Lungu; E. Alves. 2019. "Stability of beryllium coatings deposited on carbon under annealing up to 1073 K." Fusion Engineering and Design 146, no. : 303-307.

Journal article
Published: 19 December 2018 in Surface and Coatings Technology
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Bipolar Pulse High Power Impulse Magnetron Sputtering (BP-HiPIMS) was investigated and used in this work to control the ion bombardment process of growing thin films and to improve their structure and properties. Energy-resolving mass spectroscopy was used to investigate the effect of reverse target voltage on the ion energies and fluxes during BP-HiPIMS of a high-purity copper target, in argon gas. It was found that the reverse target voltage provides a wide range of ion energies and fluxes incident to the growing film, which, in turn, produce a wide variety of effects during the deposition process, improving the adhesion strength and influencing both surface and bulk properties. Fast ICCD imaging was used to investigate both HiPIMS and BP-HiPIMS plasma dynamics. The temporal and spatial distributions of plasma potential measurements were performed in order to explain the mechanisms for accelerating the ions. The topological, structural and mechanical properties of the deposited coatings were investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), thermal desorption spectroscopy (TDS), scanning electron microscopy (SEM), nanoindentation and scratch tests. The obtained results indicate an energy-enhanced deposition process during BP-HiPIMS, the deposited films being characterized by smooth surfaces, dense microstructure, small inert gas inclusions, high elastic strain to failure, scratch resistance and good adhesion to the substrate. These improvements in the films' structure and properties may be attributed to the intense and energetic ion bombardment taking place during the deposition process. During BP-HiPIMS operation, there is no net increase in the deposition rate as compared to the monopolar regime due to the re-sputtering process.

ACS Style

Ioana-Laura Velicu; Gabriela-Theodora Ianoş; Corneliu Porosnicu; Ilarion Mihaila; Ion Burducea; Alin Velea; Daniel Cristea; Daniel Munteanu; Vasile Tiron. Energy-enhanced deposition of copper thin films by bipolar high power impulse magnetron sputtering. Surface and Coatings Technology 2018, 359, 97 -107.

AMA Style

Ioana-Laura Velicu, Gabriela-Theodora Ianoş, Corneliu Porosnicu, Ilarion Mihaila, Ion Burducea, Alin Velea, Daniel Cristea, Daniel Munteanu, Vasile Tiron. Energy-enhanced deposition of copper thin films by bipolar high power impulse magnetron sputtering. Surface and Coatings Technology. 2018; 359 ():97-107.

Chicago/Turabian Style

Ioana-Laura Velicu; Gabriela-Theodora Ianoş; Corneliu Porosnicu; Ilarion Mihaila; Ion Burducea; Alin Velea; Daniel Cristea; Daniel Munteanu; Vasile Tiron. 2018. "Energy-enhanced deposition of copper thin films by bipolar high power impulse magnetron sputtering." Surface and Coatings Technology 359, no. : 97-107.

Journal article
Published: 06 December 2018 in Nuclear Materials and Energy
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Beryllium oxide (BeO) and deuteroxide (BeOxDy) have been found on the melted zone of a beryllium tile extracted from the upper dump plate of JET-ILW (2011–2012 campaign). Results have been obtained using Raman microscopy, which is sensitive to both the chemical bond and crystal structure, with a micrometric lateral resolution. BeO is found with a wurtzite crystal structure. BeOxDy is found as three different types which are not the β-phase but behaves as molecular species like Be(OD)2, O(Be-D)2 and DBeOD. The presence of a small amount of trapped D2O is also suspected. Our results therefore strongly suggest that D trapping occurs after melting through the formation of deuteroxides. The temperature increase favors the formation of crystal BeO which favors deuterium trapping through OD bonding.

ACS Style

M. Kumar; C. Makepeace; C. Pardanaud; Y. Ferro; E. Hodille; C. Martin; P. Roubin; A. Widdowson; T. Dittmar; C.H. Linsmeier; C.P. Lungu; C. Porosnicu; I. Jepu; P. Dinca; M. Lungu; O.G. Pompilian; Jet Contributors. Identification of BeO and BeOxDy in melted zones of the JET Be limiter tiles: Raman study using comparison with laboratory samples. Nuclear Materials and Energy 2018, 17, 295 -301.

AMA Style

M. Kumar, C. Makepeace, C. Pardanaud, Y. Ferro, E. Hodille, C. Martin, P. Roubin, A. Widdowson, T. Dittmar, C.H. Linsmeier, C.P. Lungu, C. Porosnicu, I. Jepu, P. Dinca, M. Lungu, O.G. Pompilian, Jet Contributors. Identification of BeO and BeOxDy in melted zones of the JET Be limiter tiles: Raman study using comparison with laboratory samples. Nuclear Materials and Energy. 2018; 17 ():295-301.

Chicago/Turabian Style

M. Kumar; C. Makepeace; C. Pardanaud; Y. Ferro; E. Hodille; C. Martin; P. Roubin; A. Widdowson; T. Dittmar; C.H. Linsmeier; C.P. Lungu; C. Porosnicu; I. Jepu; P. Dinca; M. Lungu; O.G. Pompilian; Jet Contributors. 2018. "Identification of BeO and BeOxDy in melted zones of the JET Be limiter tiles: Raman study using comparison with laboratory samples." Nuclear Materials and Energy 17, no. : 295-301.

Journal article
Published: 19 November 2018 in Nuclear Materials and Energy
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Pure Be, Be-O and Be-O-C thin coatings were deposited using high-power impulse magnetron sputtering (HiPIMS) with and without incorporation of deuterium. The coatings produced without deuterium were implanted afterwards with 15 keV 2H+ ion beams with a fluence limited to 2 × 1017 ion/cm2 in order to mitigate the damage imposed by ion irradiation and prevent a fast gas release. The as-deposited and as-implanted coatings were analysed by IBA techniques, namely by elastic and Rutherford backscattering spectrometries (EBS and RBS, respectively), nuclear reaction analysis (NRA) and by time-of-flight elastic recoil detection analysis (ToF-ERDA). Despite distinct deuterium depth profiles in the implanted samples, the results show that for the present ion implantation and deposition parameters, similar retained amounts are revealed in the films loaded by ion implantation or during the HiPIMS deposition, assuring ion implantation as a competitive and reliable method for fuel incorporation in thin Be-based films for retention studies in controlled conditions.

ACS Style

R. Mateus; C. Porosnicu; C.P. Lungu; C. Cruz; Z. Siketić; Iva Bogdanovic Radovic; A. Hakola; E. Alves; Wp Pfc Contributors. Analysis of retained deuterium on Be-based films: Ion implantation vs. in-situ loading. Nuclear Materials and Energy 2018, 17, 242 -247.

AMA Style

R. Mateus, C. Porosnicu, C.P. Lungu, C. Cruz, Z. Siketić, Iva Bogdanovic Radovic, A. Hakola, E. Alves, Wp Pfc Contributors. Analysis of retained deuterium on Be-based films: Ion implantation vs. in-situ loading. Nuclear Materials and Energy. 2018; 17 ():242-247.

Chicago/Turabian Style

R. Mateus; C. Porosnicu; C.P. Lungu; C. Cruz; Z. Siketić; Iva Bogdanovic Radovic; A. Hakola; E. Alves; Wp Pfc Contributors. 2018. "Analysis of retained deuterium on Be-based films: Ion implantation vs. in-situ loading." Nuclear Materials and Energy 17, no. : 242-247.

Conference paper
Published: 08 November 2018 in AIP Conference Proceedings
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To synthesize Carbon-Titanium (C-Ti) multilayer thin films deposited on silicon substrates was used Thermionic Vacuum Arc (TVA) method. The coated layers consisted of a base layer of about 100 nm of Carbon deposited at low evaporation rates. Subsequently, seven Carbon and Titanium layers were deposited alternatively on top of Carbon base layer, each of them has a final thickness up to 40 nm. In this study we obtained different batches of samples by variation of the substrate temperature between 0°C and 300°C, and the ion acceleration voltage applying a negative substrate bias voltage between 0V and -700V. To characterize the microstructure properties of as prepared C-Ti multilayer structures were used Electron Microscopy techniques (TEM, SEM, STEM) and Raman Spectroscopy. Results of tribological measurements are associated with the occurrence of atomic diffusion processes at Ti/C interface. To characterize the electrical conductive properties, the electrical resistance versus temperature have been measured.

ACS Style

Victor Ciupină; Cristian P. Lungu; Eugeniu Vasile; Gabriel C. Prodan; Corneliu Porosnicu; Rodica Vladoiu; Aurelia Mandes; Virginia Dinca; Virginia Nicolescu; Madalina Prodan; Radu Manu. Carbon-titanium multilayer films: Synthesis and characterization. AIP Conference Proceedings 2018, 2042, 020034 .

AMA Style

Victor Ciupină, Cristian P. Lungu, Eugeniu Vasile, Gabriel C. Prodan, Corneliu Porosnicu, Rodica Vladoiu, Aurelia Mandes, Virginia Dinca, Virginia Nicolescu, Madalina Prodan, Radu Manu. Carbon-titanium multilayer films: Synthesis and characterization. AIP Conference Proceedings. 2018; 2042 (1):020034.

Chicago/Turabian Style

Victor Ciupină; Cristian P. Lungu; Eugeniu Vasile; Gabriel C. Prodan; Corneliu Porosnicu; Rodica Vladoiu; Aurelia Mandes; Virginia Dinca; Virginia Nicolescu; Madalina Prodan; Radu Manu. 2018. "Carbon-titanium multilayer films: Synthesis and characterization." AIP Conference Proceedings 2042, no. 1: 020034.

Proceedings article
Published: 07 September 2018 in Nanostructured Thin Films XI
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Carbon-Titan (C-Ti) multilayer films were deposited on silicon substrates by means of Thermionic Vacuum Arc (TVA) method. The final thickness of the multilayer structures was up to 400nm. The coated layers consisted of a base layer of about 100nm of Carbon deposited at low evaporation rates in order to ensure its stability on the substrate. Subsequently, seven Carbon and Titanium layers were deposited alternatively on top of Carbon base layer, each of them has a final thickness up to 40nm. For this study we obtained different batches of samples by variation of the substrate temperature between 0°C and 400°C, and the ion acceleration voltage applying a negative substrate bias voltage up to -700V . A low deposition rate 0.14nm/s for C and 0.18nm/s for Ti respectively was used in order to obtain the precise thickness. The characterization of microstructure properties of as prepared C-Ti multilayer structures were done using Electron Microscopy techniques (TEM, SEM, STEM), and Raman Spectroscopy. TEM and STEM studies were performed on Philips Tecnai F30G2 at 300kV setup. Identification of the structure of the material was based on the data obtained from diffraction pattern with a Philips CM120ST using CRISP2 application, with crystalline material module (ELD). The morphology and thickness of the samples were also determined by SEM techniques with Quanta FEG450 setup. The thickness thus measured are between 155.4nm and 393.9nm. Raman spectra were measured at room temperature on a Jobin Yvon T6400 spectrometer using 514.5nm line of an Ar+ laser as the excitation source. The measurements reveal the content of diamond-like sp3 and graphite-like sp2; the ratio sp3/sp2 increases when the bias voltage increases. For tribological characteristics determination, systematic measurements were performed using a ball-on-disk tribometer made by CSM Switzerland with normal force of 0.5, 1, 2, 3N respectively. The coefficient of friction depends on the substrate temperature and on the bias voltage. To characterize the electrical conductive properties, the electrical surface resistance versus temperature have been measured using drop voltage between two ohmic contacts on the sample and drop voltage on a standard resistance in a constant current regime. Owing to metallic layer of titanium in multilayer films, mechanical and electrical properties can be improved.

ACS Style

Victor Ciupina; Rodica Vladoiu; Cristian P. Lungu; Corneliu Porosnicu; Madalina Prodan; Aurelia Mandes; Virginia Dinca; Eugeniu Vasile; Ovidiu Cupsa; Virginia Nicolescu; Gabriel C. Prodan. Nanostructured carbon-titanium multilayer films obtained by thermionic vacuum arc method. Nanostructured Thin Films XI 2018, 10731, 1073107 .

AMA Style

Victor Ciupina, Rodica Vladoiu, Cristian P. Lungu, Corneliu Porosnicu, Madalina Prodan, Aurelia Mandes, Virginia Dinca, Eugeniu Vasile, Ovidiu Cupsa, Virginia Nicolescu, Gabriel C. Prodan. Nanostructured carbon-titanium multilayer films obtained by thermionic vacuum arc method. Nanostructured Thin Films XI. 2018; 10731 ():1073107.

Chicago/Turabian Style

Victor Ciupina; Rodica Vladoiu; Cristian P. Lungu; Corneliu Porosnicu; Madalina Prodan; Aurelia Mandes; Virginia Dinca; Eugeniu Vasile; Ovidiu Cupsa; Virginia Nicolescu; Gabriel C. Prodan. 2018. "Nanostructured carbon-titanium multilayer films obtained by thermionic vacuum arc method." Nanostructured Thin Films XI 10731, no. : 1073107.

Accepted manuscript
Published: 19 July 2018 in Nuclear Fusion
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Gas seeding is often used in tokamaks to reduce the power load onto the divertor target plates. Nitrogen is the preferred seeding species because of its favourable radiative properties as well as its apparent beneficial effect on plasma confinement. However, nitrogen molecules are chemically reactive with hydrogen and its isotopes to form stable ammonia compounds. Since ammonia is a polar molecule, sticking on metal surfaces can be expected, increasing as a consequence the tritium retention which could pose a serious risk for ITER operation and maintenance. It is, therefore, important to understand the adsorption mechanism of ammonia on surfaces, investigate when the surface saturation occurs and whether ammonia adsorbs as a molecule or undergoes a dissociation on the surface. In this contribution, ammonia sticking on different fusion-relevant materials is presented. The results show a pressure-dependent ammonia sticking on tungsten, boron and stainless steel followed by a partial desorption from these surfaces while on gold and beryllium, ammonia molecules weakly adsorb and completely desorb. A detailed explanation of the two interaction mechanisms is addressed. Furthermore, the time dependence of ammonia desorption as well as the chemical state of non-desorbed residuals were investigated with X-ray Photoelectron spectroscopy. Tungsten, boron and stainless steel surfaces showed a continuous dissociation process from NH3 to NH2, NH, N and surface nitrides.

ACS Style

Marwa Ben Yaala; Laurent Marot; Roland Steiner; Lucas Moser; Gregory De Temmerman; Corneliu Porosnicu; Cristian P Lungu; M. Oberkofler; Ernst Meyer. Quartz micro-balance and in situ XPS study of the adsorption and decomposition of ammonia on gold, tungsten, boron, beryllium and stainless steel surfaces. Nuclear Fusion 2018, 58, 106012 .

AMA Style

Marwa Ben Yaala, Laurent Marot, Roland Steiner, Lucas Moser, Gregory De Temmerman, Corneliu Porosnicu, Cristian P Lungu, M. Oberkofler, Ernst Meyer. Quartz micro-balance and in situ XPS study of the adsorption and decomposition of ammonia on gold, tungsten, boron, beryllium and stainless steel surfaces. Nuclear Fusion. 2018; 58 (10):106012.

Chicago/Turabian Style

Marwa Ben Yaala; Laurent Marot; Roland Steiner; Lucas Moser; Gregory De Temmerman; Corneliu Porosnicu; Cristian P Lungu; M. Oberkofler; Ernst Meyer. 2018. "Quartz micro-balance and in situ XPS study of the adsorption and decomposition of ammonia on gold, tungsten, boron, beryllium and stainless steel surfaces." Nuclear Fusion 58, no. 10: 106012.

Journal article
Published: 11 July 2018 in Journal of Non-Crystalline Solids
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Chalcogenide amorphous materials, such as GeTe, are known to exhibit deposition dependent optical and structural properties. The formation of a single and homogeneous amorphous GeTe (a-GeTe) phase is questionable since the deposited films can be mixtures of monoelemental nanoclusters. In this work, we employed two deposition techniques, pulsed laser deposition from a polycrystalline GeTe target and co-sputtering from two distinct Ge and Te targets, respectively, to obtain a-GeTe films. To improve the homogeneity of the amorphous phase obtained by magnetron sputtering, the substrate temperature was varied from room temperature up to 180 °C. The samples were investigated by X-ray diffraction, X-ray reflectometry, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. It was found that the film mass density, optical bandgap, refractive index and absolute reflectivity become progressively larger with increasing substrate temperature, due to the minimization of voids fraction and the number of dangling bonds in the amorphous structure. Moreover, X-ray photoelectron spectroscopy results prove the formation of Ge-Te bonds and therefore of the GeTe alloy at the optimal substrate temperature of 180 °C. This study reveals the importance of optimizing the deposition conditions for obtaining a specific amorphous phase, which enables the atomic rearrangements responsible for fast phase-change needed in memory applications.

ACS Style

A.C. Galca; F. Sava; I.D. Simandan; Ioana Cristina Bucur; V. Dumitru; C. Porosnicu; C. Mihai; A. Velea. Structural and optical properties of optimized amorphous GeTe films for memory applications. Journal of Non-Crystalline Solids 2018, 499, 1 -7.

AMA Style

A.C. Galca, F. Sava, I.D. Simandan, Ioana Cristina Bucur, V. Dumitru, C. Porosnicu, C. Mihai, A. Velea. Structural and optical properties of optimized amorphous GeTe films for memory applications. Journal of Non-Crystalline Solids. 2018; 499 ():1-7.

Chicago/Turabian Style

A.C. Galca; F. Sava; I.D. Simandan; Ioana Cristina Bucur; V. Dumitru; C. Porosnicu; C. Mihai; A. Velea. 2018. "Structural and optical properties of optimized amorphous GeTe films for memory applications." Journal of Non-Crystalline Solids 499, no. : 1-7.

Journal article
Published: 01 June 2018 in Surface and Coatings Technology
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ACS Style

Vasile Tiron; Ioana-Laura Velicu; Iulian Pana; Daniel Cristea; Bogdan George Rusu; Paul Dinca; Corneliu Porosnicu; Eduard Grigore; Daniel Munteanu; Sorin Tascu. HiPIMS deposition of silicon nitride for solar cell application. Surface and Coatings Technology 2018, 344, 197 -203.

AMA Style

Vasile Tiron, Ioana-Laura Velicu, Iulian Pana, Daniel Cristea, Bogdan George Rusu, Paul Dinca, Corneliu Porosnicu, Eduard Grigore, Daniel Munteanu, Sorin Tascu. HiPIMS deposition of silicon nitride for solar cell application. Surface and Coatings Technology. 2018; 344 ():197-203.

Chicago/Turabian Style

Vasile Tiron; Ioana-Laura Velicu; Iulian Pana; Daniel Cristea; Bogdan George Rusu; Paul Dinca; Corneliu Porosnicu; Eduard Grigore; Daniel Munteanu; Sorin Tascu. 2018. "HiPIMS deposition of silicon nitride for solar cell application." Surface and Coatings Technology 344, no. : 197-203.