Персона: Крат, Степан Андреевич
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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 "Исследования и разработки в области управляемого термоядерного синтеза на токамаках ITER, Т-15 МД, MEPHIST"
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Степан Андреевич
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Теперь показываю 1 - 10 из 74
- 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.
- ПубликацияОткрытый доступPost-mortem analyses of gap facing surfaces of tungsten tiles of T-10 ring limiter(2021) Arkhipov, I.; Grashin, S.; Zibrov, M.; Pisarev, A.; Babich, Y.; Berdnikova, M.; Gasparyan, Y.; Gutorov, K.; Efimov, V.; Isaenkova, M.; Krat, S.; Krymskaya, O.; Kurnaev, V.; Stepanova, T.; Vovchenko, E.; Vizgalov, I.; Писарев, Александр Александрович; Бердникова, Мария Михайловна; Гаспарян, Юрий Микаэлович; Гуторов, Константин Михайлович; Ефимов, Виталий Сергеевич; Исаенкова, Маргарита Геннадьевна; Крат, Степан Андреевич; Крымская, Ольга Александровна; Степанова, Татьяна Владимировна; Вовченко, Евгений Дмитриевич© 2020 Elsevier B.V.Surfaces facing the gap between W tiles of the ring limiter of tokamak T-10 were analyzed after T-10 decommissioning using LIBS, SEM/EDA, XRD, TDS, and NRA techniques. Gaps with the width of 5 mm and 0.1 mm were nearly completely covered to their full depths of 22 and 15 mm, respectively, by a deposited film. The film was formed mainly by deposition of lithium that came from Li limiter and transformed in air to Li2CO3 and Li2O. Carbon was deposited from volatile hydrocarbons sputtered from the tokamak walls. Besides, carbon appeared due to chemical reaction with lithium in air. Chemical interactions of W with C, O, and Li led to formation W2C, WC, WO2, and Li2WO4. Carbides formed in W over the entire surface to the full depth of the gaps. Trapping of deuterium and helium in tiles was demonstrated. Possible influence of auto-oscillating discharges on ionization and ion trapping of C,D, and He in gaps is discussed.
- ПубликацияОткрытый доступComparison of JET inner wall erosion in the first three ITER-like wall campaigns(2021) Krat, S.; Mayer, M.; Coad, J. P.; Lungu, C. P.; Крат, Степан АндреевичThe net erosion of material from recessed areas of the JET main chamber inner wall during the first three ITERlike wall (JET-ILW) campaigns was studied using long-term samples with Be and W marker layers. The samples were analyzed using elastic backscattering spectrometry (EBS) before and after each campaign. It was found that the erosion for both Be and W was roughly homogeneously distributed in both toroidal and poloidal directions, possibly with a small maximum near the middle of the inner wall and a minimum near the bottom of the wall, as well as several toroidal distribution features. The net erosion rate of Be decreased by a factor of two between the first and the second JET-ILW campaigns, and remained unchanged during the third JET-ILW campaign. Three possible explanations are presented: a campaign to test the power handling capability of the limiter in ILW1, a change in incident particle energy distribution, and a change in limiter to divertor discharge time ratio. The net erosion rate of W remained almost unchanged through the first two JET-ILW campaigns. In the third JET-ILW campaign the net erosion rate of W from the inner wall was about 1.6 times higher than previously observed, indicating a change in the energy spectrum of particles eroding the inner wall, and the occasional addition of Kr and Xe to the fuelling.
- ПубликацияОткрытый доступAnalytical approach for description of deuterium content in deuterium-beryllium co-deposited layers(2021) De, Temmerman, G.; Krat, S.; Gasparyan, Y.; Vasina, Y.; Prishvitcyn, A. S.; Pisarev, A.; Крат, Степан Андреевич; Гаспарян, Юрий Микаэлович; Пришвицын, Александр Сергеевич; Писарев, Александр Александрович© 2021 The Author(s)Available literature data for beryllium content in D-Be co-deposited layers was modeled using newly developed model. It was shown that the model adequately describes the experimental results. An empirical scaling for the available trap concentrations as a function of deuteron energy was introduced in order to improve the agreement between the experimental data and model predictions. The limited recombination rate describes the co-deposition better than the unlimited one. Assuming two types of traps in the film with detrapping energies of 0.8–0.9 and 1.2–1.3 eV and trap concentrations of 10 at. % and 1 at. %, respectively, and the deuterium implantation energy of 15.6 eV, the average relative deviation between experimental and predicted D/Be values of 1.9 was observed, which is better than the empirical D/Be scalings.
- ПубликацияТолько метаданныеEFFECT OF PLASMA FACING MATERIAL SELECTION ON HYDROGEN ACCUMULATION IN FUSION DEVICES ВЛИЯНИЕ ВЫБОРА МАТЕРИАЛА ОБЛИЦОВКИ СТЕНОК ТЕРМОЯДЕРНЫХ УСТАНОВОК НА НАКОПЛЕНИЕ ИЗОТОПОВ ВОДОРОДА(2024) Gasparyan, Y. M.; Krat, S. A.; Гаспарян, Юрий Микаэлович; Крат, Степан Андреевич
- ПубликацияТолько метаданныеVertical stray field measurements using an electron beam in the MEPhIST-0 tokamak(2024) Vinitskiy, E. A.; Efimov, N. E.; Prishvitsyn, A. S.; Sorokin, I. A.; Krat, S. A.; Виницкий, Егор Александрович; Ефимов, Никита Евгеньевич; Пришвицын, Александр Сергеевич; Сорокин, Иван Александрович; Крат, Степан Андреевич
- ПубликацияОткрытый доступCOMPARISON OF EROSION AND DEPOSITION IN JET DURING CARBON AND ITER-LIKE CAMPAIGNS(НИЯУ МИФИ, 2015) Krat, S.; Gasparyan, Yu.; Pisarev, A.; Mayer, M.; de Saint-Aubin, G.; Bykov, I.; Coad, P.; Likonen, J.; van Renterghem, W.; Ruset, C.; Widdowson, A.; JET-EFDA, contributors; Гаспарян, Юрий Микаэлович; Крат, Степан Андреевич; Писарев, Александр АлександровичErosion of plasma facing elements in fusion devices is an important question affecting their lifetimes. Redeposition of eroded materials may lead to accumulation of hydrogen isotopes, which makes it an important problem from the perspective of radiological safety. Redeposition in layers with carbon and beryllium could be a channel for hydrogen isotope accumulation.
- ПубликацияОткрытый доступINTERACTION OF LITHUM-DEUTERIUM FILMS WITH ATMOSPHERIC GASES(НИЯУ МИФИ, 2015) Popkov,A. S.; Krat, S. A.; Gasparyan, Yu. M.; Pisarev, A. A.; Гаспарян, Юрий Микаэлович; Писарев, Александр Александрович; Крат, Степан АндреевичA choice of plasma-facing materials is one of the key issues in thermonuclear fusion reactor design. Lithium as an element with the low atomic number is a promising material for plasma-facing components (PFC) in fusion installations and a number of experiments at tokamaks already demonstrated many positive effects on plasma operation [1,2]. Lithium can be used for conditioning, PFC on the base of of capillary porous system with liquid lithium are also considered. In any way, one can expect lithium co-deposition with hydrogen isotopes at the surface of PFC and at remote areas. Lithium as a good getter can accumulate high amount of hydrogen isotopes (deuterium, tritium) that can be a problem from the safety reason. Deuterium retention and thermal desorption from lithium films formed in plasma discharge were investigated in this work.
- ПубликацияТолько метаданныеLaser-aided diagnostic of hydrogen isotope retention on the walls of the Globus-M2 tokamak(2021) Mukhin, E.; Razdobarin, A.; Minaev, V.; Novokhatsky, A.; Gasparyan, Y.; Bulgadaryan, D.; Efimov, N.; Efimov, V.; Krat, S.; Popova, M.; Sinelnikov, D.; Vovchenko, E.; Dmitriev, A.; Elets, D.; Гаспарян, Юрий Микаэлович; Ефимов, Никита Евгеньевич; Ефимов, Виталий Сергеевич; Крат, Степан Андреевич; Синельников, Дмитрий Николаевич; Вовченко, Евгений Дмитриевич; Елец, Денис Игоревич© 2021The application of the laser-aided diagnostic using the nanosecond laser for direct measurement of hydrogen concentration on the walls of the Globus-M2 tokamak is under discussion. The D release after the laser irradiation with the fluence in the range of 0.1 - 4 J/cm2 was measured in laboratory experiments at the Large MEPhI mass-monochromator facility for W-D, Ti-D films, and for the W tile exposed in the Globus-M tokamak. The desorption flux was high enough to be detected during similar measurements inside the Globus-M2 tokamak. TMAP 7 modeling of D release from W-D films was done for the relatively low laser fluence (< 1 J/cm2). A reasonable agreement with experimental data has been achieved, and the depth of analysis was estimated.
- ПубликацияОткрытый доступИЗОТОПНЫЙ ЭФФЕКТ В НАКОПЛЕНИИ ВОДОРОДА В ОСАЖДЁННЫХ ИЗ ПЛАЗМЫ ВОЛЬФРАМОВЫХ СЛОЯХ(НИЯУ МИФИ, 2024) КРАТ, С. А.; ПРИШВИЦЫН, А. С.; ГАСПАРЯН, Ю. М.; ПИСАРЕВ, А. А.; Писарев, Александр Александрович; Пришвицын, Александр Сергеевич; Крат, Степан Андреевич; Гаспарян, Юрий МикаэловичВажность изучения накопления водорода в соосаждённых из плазмы металлических слоях во многом обусловлена опасностью избыточного накопления радиоактивного изотопа трития в термоядерных установках, где со-осаждение материалов стенки с частицами работчего газа – один из основных каналов накопления водорода в установке. Так как эксперименты с использованием трития крайне затруднены технически, опасны и дороги, подавляющее большинство работ в данной области проводится с использованием дейтерия как симулятора трития. При этом предполагается, что накопление трития будет происходить идентично накоплению дейтерия. В связи со сложностью проведения экспериментов с тритием, возможно провести опыты по сравнению свойств протия и дейтерия и сделать некоторые оценки в части трития на основе полученных данных.