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Ефимов, Виталий Сергеевич

Организационные подразделения

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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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Ефимов

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Виталий Сергеевич

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Теперь показываю 1 - 10 из 64

Открытый доступ
CORRELATION OF DEUTERIUM RETENTION WITH CRYSTALLINE STRUCTURE IN DENSE AND DISORDERED TUNGSTEN COATINGS
(НИЯУ МИФИ, 2017) Ogorodnikova, O. V.; Ruset, C.; Dellasega, D.; Pezzoli, A.; Passoni, M.; Sugiyama, K.; Gasparyan, Yu.; Efimov, V.; Ефимов, Виталий Сергеевич; Гаспарян, Юрий Микаэлович; Огородникова, Ольга Вячеславовна
Dense nano-structured tungsten (W) coatings are used as plasma-facing materials in current tokamaks and thick coatings are suggested to be used also for the future fusion devices, ITER and DEMO. In this study, deuterium (D) retention in various W coatings was investigated to understand dependences of the D retention on the crystalline structure of each W coating and on the substrate material.
Только метаданные
Deuterium 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.
Открытый доступ
ЗАМЕЩЕНИЕ ИЗОТОПОВ ГЕЛИЯ В ВОЛЬФРАМЕ ПРИ ПОСЛЕДОВАТЕЛЬНОМ ИОННОМ ОБЛУЧЕНИИ
(НИЯУ МИФИ, 2023) Умеренкова, А. С.; Гаспарян, Ю. М.; Арутюнян, З. Р.; Ефимов, В. С.; Сергеев, Н. С.; Сорокин, И. А.; Остойич, Н.; Остойич, Никола; Гаспарян, Юрий Микаэлович; Умеренкова, Анастасия Сергеевна; Ефимов, Виталий Сергеевич; Сорокин, Иван Александрович; Арутюнян, Зорий Робертович; Сергеев, Никита Сергеевич
Helium isotope exchange in tungsten during sequential irradiation by 3He and 4He ions at room temperature was investigated. Tungsten samples were irradiated in two ways: by 3 keV mass-separated ion beams, or by low energy ions in plasma discharge. The He amount in W after irradiation was measured using ex-situ (up to 2500 K) thermal desorption spectroscopy. Despite the very high binding energy of He with lattice defects in W, a very high efficiency of He isotope exchange was observed.
Открытый доступ
SURFACE MODIFICATIONS OF W-BASED MATERIALS UNDER HELIUM AND DEUTERIUM ION IMPLANTATION
(НИЯУ МИФИ, 2021) Ogorodnikova, O. V.; Klimov, N. S.; Gasparyan, Yu. M.; Harutyunyan, Z. R.; Efimov, V. S.; Kovalenko, D.; Gutarov, K.; Poskakalov, А. G.; Kharkov, M. M.; Kaziev, A. V.; Харьков, Максим Михайлович; Гаспарян, Юрий Микаэлович; Казиев, Андрей Викторович; Ефимов, Виталий Сергеевич; Огородникова, Ольга Вячеславовна
In a thermonuclear reactor, materials will be irradiated with hydrogen isotopes and helium (He), neutrons, and heat fluxes. Tungsten (W) and dense nano-structured tungsten (CMSII) coatings are used as plasma-facing materials in current tokamaks and suggested to be used for future fusion devices. In this regard, the study of the accumulation of He and deuterium (D) in W based materials and corresponding surface modifications under normal operation conditions and transient events appears necessary for assessment of safety of fusion reactor due to the radioactivity of tritium and material performance and for the plasma fuel balance. Therefore, in this work, irradiation of W-based materials with D and He ions in stationary regime and in quasi-stationary high-current plasma gun QSPA-T below and above the melting threshold has been performed. In QSPA-T, a pulse duration was 1 ms and number of pulses was varied from one to thirty. In stationary plasma loads, ion energy was varied from 20 to 3 keV, temperature 300-1200 K and flux/fluence 1017-1021 at/m2s/1020-1025 at/m2.
Открытый доступ
HELIUM 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 Робертович
Helium (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.
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Surface 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.
Только метаданные
Deuterium retention in W-Ta alloys after low-temperature plasma irradiation and gas exposure
(2021) Bobyr, N. P.; Efimov, V. S.; Khripunov, B. I.; Kozlov, D. A.; Ефимов, Виталий Сергеевич
In this study plates of W, W-xTa alloys (x = 1; 3; 5 concentration in at.%) with a large grain size were used as experimental samples. All the samples were polished to a mirror surface and outgassed in vacuum at 1100 K during 2 h. Sets of W, W-1Ta, W-3Ta, W-5Ta samples were irradiated with low-temperature D plasma up to fluences of 2e25 D m(-2). Other sets of W, W-1Ta, W-3Ta, W-5Ta samples were exposed in D-2 gas in a temperature range of 425 divided by 625 K and pressure 10(3) Pa. The D retention in W and W-Ta alloys was measured by thermal desorption spectroscopy (TDS). An influence of Ta dopant on deuterium retention in W was observed. The dopant of tantalum slightly reduces the accumulation of deuterium in tungsten during gas exposure. Increasing temperature of samples during D-plasma irradiation from 415 K to 615 K reduces deuterium retention up to 2 orders of magnitude.
Открытый доступ
ИССЛЕДОВАНИЕ НАКОПЛЕНИЯ ДЕЙТЕРИЯ В БЕРИЛЛИИ ПРИ ОБЛУЧЕНИИ МОЩНЫМИ ИМПУЛЬСНЫМИ ПОТОКАМИ ПЛАЗМЫ
(НИЯУ МИФИ, 2015) Ефимов, В. С.; Гаспарян, Ю. М.; Писарев, А. А.; Куприянов, И. Б.; Порезанов, Н. П.; Ефимов, Виталий Сергеевич; Писарев, Александр Александрович; Гаспарян, Юрий Микаэлович
Deuterium accumulation in beryllium with pulsed power plasma flows irradiation was investigated by means of thermal desorption spectroscopy. Two grades of beryllium (TGP-56FW and S-65C) were analyzed in this work. Deuterium desorbed mainly in the temperature region of 800÷1400 K with a maximum around 1200 K. Deuterium retention in S- 65C beryllium grade was three times higher than in TGP-56FW.
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Deuterium trapping in the subsurface layer of tungsten pre-irradiated with helium ions
(2021) Kanashenko, S.; Harutyunyan, Z.; Gasparyan, Y.; Ryabtsev, S.; Efimov, V.; Ogorodnikova, O.; Pisarev, A.; Арутюнян, Зорий Робертович; Гаспарян, Юрий Микаэлович; Ефимов, Виталий Сергеевич; Огородникова, Ольга Вячеславовна; Писарев, Александр Александрович
© 2021The effect of He-induced defects in tungsten on the efficiency of trapping of deuterium ions in the subsurface layer was studied using thermal desorption spectroscopy (TDS). The W sample was pre-irradiated with 3 keV helium ions at room temperature and various fluences in the range of 1019 – 5 × 1021 He/m2. Then, it was exposed to a probe fluence of 1019 D/m2 of 2 keV D3+ (670 eV/D) ions, and in-situ TDS was performed. The de-trapping energy for D atoms increased with the increase of the He pre-irradiation fluence. On the other hand, a strong decrease in the D retention was observed if the He fluence increased above 1021 He/m2. At the highest He fluence of 5 × 1021 He/m2 deuterium trapping was possible only after partial release of He atoms. By comparison of experimental TDS spectra with modeling, the de-trapping energies of D atoms from various defects were estimated.
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Effect of the presence of helium in tungsten on deuterium retention
(2021) Kanashenko, S.; Ogorodnikova, O. V.; Harutyunyan, Z. R.; Gasparyan, Y. M.; Efimov, V. S.; Kharkov, M. M.; Kaziev, A. V.; Огородникова, Ольга Вячеславовна; Арутюнян, Зорий Робертович; Гаспарян, Юрий Микаэлович; Ефимов, Виталий Сергеевич; Харьков, Максим Михайлович; Казиев, Андрей Викторович
© 2021Tungsten (W) samples were pre-irradiated with low-energy helium (He) ions with an energy of 80 eV, flux of 1021 He/m2s, at a sample temperature of 1200–1250 K in a inductively coupled plasma (ICP) source facility. Such irradiation conditions led to a formation of a nano-structured surface layer of tungsten, called ‘fuzz’. These samples were then irradiated with D3+ ions with an energy of 2 keV and small doses of 1019 D/m2 at room temperature and in-situ thermal desorption analysis (TDS) was performed. It was found that the main factor determining the deuterium (D) retention in W samples pre-irradiated with helium is the concentration of helium below the surface, namely, the D retention was increased with decreasing the He concentration until the nanostructured W ‘fuzz’ was removed. The effect of nano-structured tungsten ‘fuzz’ is only in a decrease of the reflection coefficient of deuterium ions compared to a smoother surface, resulting in the increase of the D influx into W and, consequently, increase of the D retention. However, this increase has a minor effect on the D retention compared to the He concentration in the subsurface layer of W.