2019, Hwangbo, D., Kajita, S., Ohno, N., Sinelnikov, D., Bulgadaryan, D., Kurnaev, V., Синельников, Дмитрий Николаевич

© 1973-2012 IEEE.Field emission from tungsten surfaces with nano-tendril bundles formed after exposure to helium plasma with nitrogen or neon impurities was measured using a vacuum diode device. Field enhancement factor and effective emission area were calculated using the Fowler-Nordheim formula and compared for different types of nanostructures. The field enhancement factor for these structures can reach several thousands and the effective emission area can be more than 1000 nm2. Anode luminescence was detected using long-exposure photography and allowed for estimation of current density near the anode. Unipolar arc tracks were observed on the samples with the highest field emission intensity. We show that field emission from nano-tendril bundles is much higher than that from tungsten fuzz or pure tungsten, and fusion-relevant plasma conditions may lead to arc initiation.

2019, Mamedo, N. V., Kurnaev, V. A., Sinelnikov, D. N., Mamedov, I. M., Синельников, Дмитрий Николаевич, Мамедов, Никита Вадимович

Low-energy (1-20 keV) ion scattering spectroscopy is the widespread method of surface analysis [1,2]. The surface layer composition can be reconstructed from narrow peaks in the energy spectra of the scattered inert gas ions and recoil ions [3]. The main advantage of the surface analysis using inert gas ions is the high sensitivity to the first layer of surface atoms. This is due to the low initial energy of the ions (and therefore small ion penetration depth) and the high neutralization probability of the reflected ions, which increases with the penetration depth of the incident particle into the solid [3]. However, for quantitative surface analysis, it is extremely important to determine the neutralization probability (or the probability of ion survival), since this method usually detects reflected ions only.

2019, Bulgadaryan, D., Sinelnikov, D., Kurnaev, V., Efimov, N., Ефимов, Никита Евгеньевич, Синельников, Дмитрий Николаевич

Low- and medium-energy ion scattering (LEIS/MEIS) are widely used techniques of surface analysis [1–4]. Conventional LEIS/MEIS setups utilize noble gas ions and electrostatic energy analyzers that makes these methods very sensitive to composition of the uppermost atomic layers of an analyzed sample. However, high neutralization probability of noble gas ions restricts LEIS/MEIS depth profiling capabilities [5]. The use of hydrogen ions with lower neutralization probability instead of noble gas provides possibility to measure the thickness of surface layer if its atomic mass is very different from that of underlying target, that is the case e.g. in nanoelectronics [6] or for redeposition of plasma-facing materials in fusion devices [7]. In this work we present simulated and experimental data on implementation of keV-energy proton scattering (KEPS) for surface analysis.

2019, Bulgadaryan, D., Sinelnikov, D., Kurnaev, V., Efimov, N., Borisyuk, P., Lebedinskii, Y., Синельников, Дмитрий Николаевич, Ефимов, Никита Евгеньевич, Борисюк, Петр Викторович, Лебединский, Юрий Юрьевич

© 2018 Elsevier B.V. Hydrogen ions are not widely used in low or medium-energy ion scattering spectroscopy. However, in certain cases, the use of non-destructive hydrogen ions with low nuclear stopping may provide additional information compared with noble gas ions. In this work, we describe in situ analysis of nanometer layer deposition of Au on Si and vice versa using keV-energy proton scattering spectroscopy. Ion beam sputtering and thermal evaporation were used for deposition of surface layers. The maximum thickness of deposited layers was measured with X-ray photoelectron spectroscopy and surface profiler. The accuracy of in situ surface layer thickness determination with energy spectra of scattered protons is discussed.

2024, Ефимов, Н. Е., Синельников, Д. Н., Гришаев, М. В., Гаспарян, Ю. М., Ефимов, В. С., Крат, С. А., Гаспарян, Юрий Микаэлович, Ефимов, Никита Евгеньевич, Гришаев, Максим Валерьевич, Синельников, Дмитрий Николаевич

В работе проведено сравнение сигналов лазерно-ассистированной масс-спектрометрии для двух длительностей лазерных импульсов (15 нс и 80 пс) на примере дейтерированных вольфрамовых пленок и образцов титан−ванадиевого сплава. Представлена методика подготовки насыщенных дейтерием образцов, обеспечивающая хорошо повторяющийся во времени выход дейтерия при нескольких последовательных выстрелах лазером, что может быть использовано для юстировки диагностической системы. Получена экспериментальная зависимость интегрального выхода дейтерия из исследуемых материалов от плотности энергии в импульсе. Продемонстрирована высокая чувствительность методики, а также слабая зависимость от длительности импульса лазерного излучения. Отмечено значительное изменение концентрации дейтерия в приповерхностном слое вольфрамовой пленки в ходе контакта с атмосферой.

2023, Grishaev, M. V., Efimov, N. E., Sinelnikov, D. N., Nikitin, I. A., Gasparyan, Y. M., Vovchenko, E. D., Вовченко, Евгений Дмитриевич, Синельников, Дмитрий Николаевич, Ефимов, Никита Евгеньевич, Гришаев, Максим Валерьевич, Гаспарян, Юрий Микаэлович, Никитин, Иван Андреевич

One of the most detrimental phenomena in fusion research is the interaction of plasma with a surface of a first wall and in-chamber elements. It causes erosion of the plasma-facing components (PFC), which in turn results in a degradation of plasma parameters due to transport of erosion products into the hot plasma. On the other hand, these processes cause re-deposition of the eroded material together with fuel components (deuterium and tritium). This is the dominant mechanism for fuel retention in PFC.

2023, Efimov, N. E., Sinelnikov, D. N., Wang, Y., Harutyunyan, Z. R., Gasparyan, Y. M., Grishaev, M. V., Nikitin, I. A., Tan, X., Синельников, Дмитрий Николаевич, Ефимов, Никита Евгеньевич, Арутюнян, Зорий Робертович, Никитин, Иван Андреевич, Гаспарян, Юрий Микаэлович, Гришаев, Максим Валерьевич

One of the challenging problems which arise in the controlled nuclear fusion is related to the design and material choice of plasma facing components for the future reactors. Tungsten is considered to be one of the most suitable candidates due to its high melting point, thermal conductivity and relatively low erosion rate, and, therefore, it is planned to be used in nextgen facilities like ITER and DEMO. However, under high neutron fluxes its stable isotopes may form radioactive ones. Being not so hazardous while it is inside the reactor, in case of a loss of coolant accident (LOCA) a volatile oxide of W and of its transmutation products may appear, which is undesirable. A possible solution to avoid the release of the radioactive oxides is the use of self-passivating W-Cr-Y alloys [1], which under LOCA scenarios forms on the surface a chromium oxide, preventing the formation of tungsten oxide. Such alloys are of the great interest now, especially when it comes to analyzing the dynamics of the chromium release to the outermost layers [2,3]. In this work, capabilities of low energy ion scattering spectroscopy (LEIS) with small angle scattering to the characterization the surface morphology of W-11,4Cr-0,6Y after pre-annealing at different temperatures are revealed.

2023, Sinelnikov, D. N., Gasparyan, Y. M., Grishaev, M. V., Efimov, N. E., Krat, S. A., Nikitin, I. A., Крат, Степан Андреевич, Гаспарян, Юрий Микаэлович, Синельников, Дмитрий Николаевич, Никитин, Иван Андреевич, Ефимов, Никита Евгеньевич, Гришаев, Максим Валерьевич

Hydrogen isotopes retention in thermonuclear fusion reactors is limited due to safety regulations and should be well controlled. Surface conditions can strongly affect accumulation rates of hydrogen isotopes in the bulk of plasma facing materials. Therefore, in vacuo methods of surface composition control may help to investigate mechanisms of this effects.

2021, Efimov, N. E., Sinelnikov, D. N., Bulgadaryan, D. G., Gasparyan, Y. M., Vovchenko, E. D., Marenkov, E. D., Маренков, Евгений Дмитриевич, Ефимов, Никита Евгеньевич, Вовченко, Евгений Дмитриевич, Синельников, Дмитрий Николаевич, Гаспарян, Юрий Микаэлович

One of the critical issues on the way to controlled nuclear fusion is related to plasma wall interaction. Such interaction leads to co-deposition of hydrogen isotopes together with eroded first wall materials. It is known that the deuterium-tritium (DT) mixture will be used in ITER and future fusion devices as a fuel. So as the accumulation of radioactive tritium in the machines is limited by the nuclear license, there is a need for some remote fuel retention monitoring system. In current devices, the total fuel amount is determined from the gas balance (difference between input and output flows) measurements and from a post mortem analysis of plasmafacing components. One of the most promising techniques which can be applied in situ in tokamaks is based on laser irradiation of the surface of interest followed by mass- or optical spectroscopy. Such a technique was already applied in TEXTOR tokamak to the hydrogenic carbon layers [1], and it is included in the task list of ITER with a high priority.

2023, Лобанова, Л. Г., Афанасьев, В. П., Гришаев, М. В., Ефимов, Н. Е., Никитин, И. А., Синельников, Д. Н., Синельников, Дмитрий Николаевич, Никитин, Иван Андреевич, Ефимов, Никита Евгеньевич, Гришаев, Максим Валерьевич

Calculation method of reflected from layered inhomogeneous solids light ions density fluxes is constructed. The method is based on analytically calculated and experimentally received reflection functions from homogeneous solids. Transmission function is calculated in Fokker-Plank approximation. Analytical results are verified on a base on comparison with experimental results.