Персона: Гаспарян, Юрий Микаэлович
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Институт лазерных и плазменных технологий
Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.
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Руководитель научной группы "Плазменные и лазерные технологии новых материалов для ядерной и термоядерной энергетики"
Руководитель научной группы -Международный центр ядерных компетенций (МЦЯДКОМ)
Руководитель научной группы -Международный центр ядерных компетенций (МЦЯДКОМ)
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Юрий Микаэлович
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- ПубликацияТолько метаданныеThe Project of MEPhIST Tokamak(2019) Kurnaev, V. A.; Vorobyov, G. M.; Nikolaeva, V. E.; Krat, S. A.; Melnikov, A. V.; Ivanov, D. P.; Gasparyan, Y. M.; Крат, Степан Андреевич; Мельников, Александр Владимирович; Гаспарян, Юрий Микаэлович© 2019, Pleiades Publishing, Ltd.The concept of the small spherical tokamak project is described, the main objectives of the project are to increase competencies at the University in the training of personnel in the field of physics and technologies of controlled thermonuclear fusion, as well as attracting young people to this area. The implementation of the project also implies giving impetus and new opportunities for improving the methods of plasma diagnostics developed at the University, studies on the plasma surface interactions and computer simulation of processes in the plasma and on the plasma facing surfaces. The installation has a large radius of 25 cm, an aspect ratio of less than 2, and a vertical elongation of ∼ 3, which allows, in principle, for small sizes and costs of the installation, taking into account the subsequent increase in the toroidal field to ∼ 2 T, to carry out important studies for progress in plasma performance in tokamaks. Namely, research on physics of plasma confinement, current drive with RF power and plasma interaction with materials. The project includes a phased implementation with a multiple increase in the magnetic field and plasma current, as well as the possibility of quick and convenient access to the internal elements of the discharge chamber and the simultaneous use of a large number of diagnostics.
- ПубликацияТолько метаданныеDeuterium and helium retention in W with and without He-induced W ‘fuzz’ exposed to pulsed high-temperature deuterium plasma(2019) Tokitani, M.; Ogorodnikova, O. V.; Klimov, K. S.; Poskakalov, A. G.; Kaziev, A. V.; Kharkov, M. M.; Efimov, V. S.; Gasparyan, Y. M.; Volkov, N. V.; Alimov, V. K.; Огородникова, Ольга Вячеславовна; Климов, Николай Сергеевич; Казиев, Андрей Викторович; Харьков, Максим Михайлович; Ефимов, Виталий Сергеевич; Гаспарян, Юрий Микаэлович© 2018 Elsevier B.V. In the present work, helium (He) was incorporated into tungsten (W) samples by inductively coupled plasma (ICP) source above the threshold of He-induced W ‘fuzz’ formation on W surface. Then, W samples with and without nano-structured W ‘fuzz’ were exposed to pulsed heat loads using deuterium (D) plasma in quasi-stationary high-current plasma gun QSPA-T. The pulse duration was 1 ms and number of pulses was varied from one to thirty to simulate ITER transient events with surface heat load parameters relevant to edge-localized-mode (ELM) impacts. The irradiation was performed below and above the W melting threshold. The D and He retention in each irradiated sample was measured by a method of thermal desorption spectroscopy. We examined the impact of (i) ELMs-like events and (ii) formation of He-induced nano-structured ‘fuzz’ on the D retention in W. We found that the D retention was the highest for samples irradiated by plasma gun above the melting threshold after thirty pulses. Moreover, the D retention after 10 pulses of deuterium plasma gun exposure was higher than that after stationary low-energy plasma exposure at sample temperature of either 600 or 700 K indicating the dominate influence of ELM's-like events on the D retention compared to normal operation regime. The D retention in W samples with the presence of He-induced W ‘fuzz’ was slightly smaller than without that after one pulse of plasma gun exposure with heat load below the W melting temperature. The W ‘fuzz’ was not disappear in this loading conditions, only the length and thickness of nano-structured W fibres were reduced by factors of ∼4 and ∼2, respectively. The He concentration in W with W ‘fuzz’ was decreased by a factor of about 3 after one pulse of plasma gun exposure. The results obtained give possibility to assess the particle retention in divertor areas subjected to high thermal loads at different operation regimes.
- ПубликацияОткрытый доступHELIUM THERMAL DESORPTION FROM TUNGSTEN AFTER ION BEAM IRRADIATION AT ELEVATED TEMPERATURES(НИЯУ МИФИ, 2019) Ryabtsev, S. A.; Gasparyan, Yu. M.; Harutyunyan, Z. R.; Efimov, V. S.; Aksenova, A. S.; Pisarev, A. A.; Писарев, Александр Александрович; Ефимов, Виталий Сергеевич; Гаспарян, Юрий Микаэлович; Арутюнян, Зорий РобертовичHelium (He) is a product of deuterium-tritium reaction, so appearance of helium impurities will be unavoidable. In addition to He implantation from fusion plasma, He can be introduced into material by both neutron irradiation and tritium radioactive decay. Presence of He in plasma-facing materials may significantly influence their mechanical properties and surface morphology [1, 2], as well as hydrogen isotope recycling [3, 4]. Tungsten (W) will be used as a plasma-facing material in ITER divertor [5], and it is considered also for application in future fusion devices. Therefore, investigation of He interaction with W is of great interest.
- ПубликацияОткрытый доступMODELING OF CO-DEPOSITION OF HYDROGEN WITH SPUTTERED METALS(НИЯУ МИФИ, 2019) Krat, S.; Gasparyan, Yu.; Vasina, Ya.; Prishvytsin, A.; Pisarev, A.; Крат, Степан Андреевич; Гаспарян, Юрий МикаэловичHydrogen accumulation in fusion devices is a serious issue from the viewpoint of radiation safety, as the total amount of radioactive tritium is strictly controlled. It also affects plasma parameters, as hydrogen accumulated in the device can be released during the discharge due to the plasma-wall interaction. One of the main channels for hydrogen accumulation is co-deposition, wherein hydrogen is deposited onto a surface together with particles of the wall material previously eroded from some other area of the fusion device’s wall by plasma. Such co-deposition can lead to accumulation of thick layers of material containing large amounts of hydrogen in hard to reach areas of the installations, such as pump lines or shadowed areas of the divertor in tokamak devices. The hydrogen content in such codeposited layers can reach tens of atomic percent, and, in the case of hydrogen active materials, such as carbon, even exceed unity. Hydrogen content in such films depends strongly on a number of co-deposition parameters, such as the deposition rate, temperature of the surface on which co-deposition occurs, hydrogen flux to the surface during deposition and others. This makes purely empirical approach to prediction of hydrogen accumulation in codeposited layers in fusion devices very difficult requiring exhaustive experimental testing in the full range of parameters that can occur in fusion devices. Such approach is not always feasible or economically viable, especially when attempting to predict hydrogen accumulation in future devices. Because of this, an approach is preferable that could provide quantitative predictions via computationally cheap predictive modeling of plasma-wall interactions.
- ПубликацияОткрытый доступHYDROGEN CO-DEPOSITION WITH METALS IN PLASMA DISCHARGE(НИЯУ МИФИ, 2017) Krat, S. A.; Gasparyan, Yu. M.; Vasina, Ya. A.; Pisarev, A. A.; Писарев, Александр Александрович; Крат, Степан Андреевич; Гаспарян, Юрий МикаэловичDeposition of a single element film is always accompanied by co-deposition of a certain amount of other elements. This can be done properly to improve properties of the coating or due to contamination by impurities. In the field of thermonuclear fusion research, where hydrogen isotopes are used as a fuel, co-deposition with sputtered material from the wall is one of major mechanisms of hydrogen isotopes accumulation in the installation. Since D-T fuel will be used in ITER and future fusion reactors, accumulation of radioactive tritium will limit the lifespan of the installations due to safety concerns. For example, tritium accumulation in ITER is limited by 1 kg. This is why carbon materials were not accepted for the use in ITER. Basing on experiments, it was predicted that the safety limit could be reached after 100 of shots with tritium. Recent experiments in JET [1] demonstrated in the case of “ITER-like” wall (first wall – Be, divertor area - tungsten) accumulation of deuterium fuel in the co-deposits was 20 times lower than in the full-carbon wall campaign. This is both due to smaller amount of co-deposits and smaller concentration of deuterium in them.
- ПубликацияОткрытый доступDEUTERIUM RE-EMISSION AND THERMAL DESORPTION FROM IRON AND EUROFER(НИЯУ МИФИ, 2017) Ryabtsev, S. A.; Gasparyan, Yu. M.; Ogorodnikova, O. V.; Harutyunyan, Z. R.; Pisarev, A. A.; Арутюнян, Зорий Робертович; Огородникова, Ольга Вячеславовна; Писарев, Александр Александрович; Гаспарян, Юрий МикаэловичReduced-activation ferritic-marthensitic (RAFM) steels, such as Eurofer, are considered as candidates for structural materials in fusion reactors due to the high thermal conductivity, the low thermal expansion coefficient and good resistance to radiation swelling. There are also some concepts of fusion reactors, where RAFM steels also considered as material for plasma-facing components. In this regard, the key aspects of hydrogen (H) isotopes interaction with RAFM steels, such as tritium (T) retention and migration in these materials are particularly important as a point of safety concern.
- ПубликацияТолько метаданныеSurface Structure Modification and Deuterium Retention in Tungsten under Pulsed Plasma Loads(2019) Poskakalov, A. G.; Klimov, N. S.; Gasparyan, Y. M.; Ogorodnikova, O. V.; Efimov, V. S.; Климов, Николай Сергеевич; Гаспарян, Юрий Микаэлович; Огородникова, Ольга Вячеславовна; Ефимов, Виталий Сергеевич© 2019, Pleiades Publishing, Ltd.Modification of the surface layer and deuterium accumulation in tungsten targets under plasma irradiation in a quasi-stationary plasma accelerator with an intrinsic magnetic field QSPA-T, which reproduces the conditions (plasma thermal load of 0.2-5 MJ/m2, pulse duration of 0.1-1.2 ms) typical of ELM events in ITER, are studied. Using a scanning electron microscope, structure modifications at the surface and in the bulk after deuterium plasma irradiation are analyzed. The observed changes in the near-surface layer are compared with the calculated data on the change in the internal structure of tungsten under intense thermal action obtained as a result of the numerical solution of the heat conduction problem. The total deuterium retention in the samples was measured using thermal desorption spectroscopy, and it was in the range of (3-4) × 1016 particles/cm2 for the samples melted during plasma exposure. These numbers exceed by an order of magnitude the values obtained for samples without traces of melting.
- ПубликацияТолько метаданныеHelium retention in tungsten irradiated with He+ ion beam at elevated temperatures(2019) Kanashenko, S.; Ivanov, Y.; Ryabtsev, S.; Gasparyan, Y.; Efimov, V.; Harutyunyan, Z.; Aksenova, A.; Poskakalov, A.; Pisarev, A.; Гаспарян, Юрий Микаэлович; Ефимов, Виталий Сергеевич; Арутюнян, Зорий Робертович; Аксенова, Александра Сергеевна; Писарев, Александр Александрович© 2019Helium (He) retention in re-crystallized tungsten (W) irradiated with He+ ions at elevated temperatures (700–1200 K) and fluences in the range of 1020–1022 He/m2 was investigated by means of thermal desorption spectroscopy (TDS). Corresponding surface modifications were analyzed by scanning electron microscopy. Blisters were observed after irradiation at 700 and 1000 K, while the increase of the irradiation temperature up to 1200 K led to development of a complex sponge-like structure on the W surface. Significant surface transformations correlated with appearance of low temperature peaks in TDS spectra below the irradiation temperature. Possible mechanisms and explanations are discussed.
- ПубликацияОткрытый доступElastic backscattering as a method for the measurement of the integral lithium content in thin films on fusion-relevant substrates(2019) Mayer, M.; Krat, S.; Vasina, Y.; Prishvitsyn, A.; Gasparyan, Y.; Pisarev, A.; Крат, Степан Андреевич; Пришвицын, Александр Сергеевич; Гаспарян, Юрий Микаэлович; Писарев, Александр Александрович© 2019 Elsevier B.V.Different ion beam analysis techniques for the study of thin lithium-containing layers on top of fusion relevant materials are discussed and compared to each other. Elastic backscattering analysis (EBS) with protons is determined to be one of the most promising techniques and allows measurements of Li layers with thicknesses from ∼100 nm up to ∼600 μm, as shown by SIMNRA simulations. The best sensitivity for thin films (∼100 nm) can be achieved using 4 MeV protons with 170° scattering detection angle for layers on Mo and W substrates, and 2 MeV for C substrates. Experimentally EBS measurements were successfully tested for Li films with thicknesses from ∼50 nm up to ∼400 nm after air exposure. The Li films become strongly inhomogeneous and require averaging over multiple measurements in nearby areas. This necessitates averaging over multiple nearby measurement points, and limits the overall precision of the measurement.
- ПубликацияТолько метаданныеTemperature dependence of hydrogen co-deposition with metals(2019) Gasparyan, Y.; Krat, S.; Davletiyarova, A.; Vasina, Y.; Pisarev, A.; Гаспарян, Юрий Микаэлович; Крат, Степан Андреевич; Писарев, Александр Александрович© 2019 Elsevier B.V. The deuterium retention in aluminum and molybdenum films co-deposited in magnetron discharge has been measured in a wide range of substrate temperatures (from RT to 800 K) by means of thermal desorption spectroscopy. A multi-step temperature dependence was observed, which was compared with the diffusion based model and previous experimental data for tungsten films. The key role of lattice defects in deuterium trapping was demonstrated. The highest D retention among the investigated materials was observed in W films, which have the lowest H solubility, but the highest binding energies of hydrogen with defects. The detrapping energies and concentrations of defects in the films were estimated on the base of the model, and the energies are consistent with the data for bulk materials.