Персона: Мельников, Александр Владимирович
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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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Мельников
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Александр Владимирович
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- ПубликацияТолько метаданныеComparison of Plasma Heating at First and Second Electron Cyclotron Harmonics in the T-10 Tokamak(2020) Dnestrovskij, Y. N.; Danilov, A. V.; Dnestrovskij, A. Y.; Klyuchnikov, L. A.; Melnikov, A. V.; Мельников, Александр Владимирович© 2020, Pleiades Publishing, Ltd.Abstract: In the T-10 tokamak, the results of plasma heating at the first and second electron cyclotron (EC) harmonics differ substantially. However, the problem is multi-parametric, so it is impossible to estimate the heating quality by sight. In this work, the analysis of heating at both harmonics is provided with two transport models, which were constructed separately for simulation in each mode. For the heating on the second harmonic, we solve the inverse problem of determining the profile of the absorbed power from the experimental electron temperature profile. In this mode, we are able to determine both the deposited power profile and the ratio of absorbed to deposited power. It is shown that at low plasma densities, this ratio is small, which, apparently, is a consequence of the low absorption of the heating waves during their single pass though the plasma. During the heating at the second harmonic, the absorbed power profile is much flatter than predicted by ray tracing calculations of EC waves. Multi-pass wave absorption with random reflections from the corrugated chamber wall leads to such absorption profiles. At high plasma densities, the absorbed power is close to the input power. However, in this case, the results at the second harmonic are worse than the results obtained at the first harmonic due to the flatter absorbed density profile.
- ПубликацияТолько метаданныеMeasurements of 2D poloidal plasma profiles and fluctuations in ECRH plasmas using the heavy ion beam probe system in the TJ-II stellarator(2020) Sharma, R.; Khabanov, P. O.; Melnikov, A. V.; Hidalgo, C.; Мельников, Александр Владимирович2D poloidal contour plots of plasma potential, plasma density, and their fluctuations have been measured in low density plasmas sustained by Electron Cyclotron Resonance Heating using a heavy ion beam probe (HIBP) system in the TJ-II stellarator. A HIBP has been used in the new energy scanning mode to obtain the measurements for a 2D poloidal cross section of the stellarator. The 2D map for the absolute plasma potential shows a local maximum in the plasma core as expected in low density plasma scenarios. Fluctuations in the HIBP secondary ion current, as a proxy of plasma density fluctuations, appear both in positive and negative density gradient regions, with a normalized level of density fluctuations higher in the negative density gradient region. The TJ-II innovative experimental setup developed using a dual HIBP diagnostic paves the way for model validation on core plasma potential asymmetries and particle transport and fluctuations under positive and negative density gradient scenarios.
- ПубликацияТолько метаданныеHEAVY ION BEAM PROBING CONCEPTUAL DESIGN FOR THE GLOBUS-M2 TOKAMAK(2020) Khabanov, P. O.; Melnikov, A. V.; Minaev, V. B.; Komarov, A. D.; Мельников, Александр ВладимировичThe paper discusses the application of the heavy ion beam probe (HIBP) diagnostic to the Globus-M2 spherical tokamak Probing beam trajectory calculations were conducted to find the optimal position for HIBP primary and secondary beam-linesin the realistic machine geometry. Three configurations of the vacuum vessel ports of Globus-M2 were considered for the regime with toroidal magnetic field B-tor =0.7 T and plasma current I-pl( )=0.5 MA. The optimal probing scheme with the widest area of the plasma cross-section covered by the detector grid was selected. For this scheme, the secondary beam-line was proposed.
- ПубликацияТолько метаданныеHIGH-INTENSITY CESIUM ION BEAMS FOR HIBP DIAGNOSTICS(2020) Krupnik, L. I.; Barcala, J.; Chmyga, O. O.; Deshko, G. M.; Melnikov, A. V.; Мельников, Александр ВладимировичThe goal of the research is to expand the capabilities of the heavy ion beam probing (HIBP) diagnostic. HIBP is a unique diagnostic, capable to measure plasma potential, density and their fluctuations, as well as the poloidal magnetic field fluctuations in the core and edge plasmas. The sensitivity of the diagnostic is determined by the level of the output signal related to the instrumental noise. The level of the probing beam current should be as high as possible, especially for measurements at the periphery with low output signal due to low plasma density, and in the core, where the beam is attenuated due to the high plasma density. Optimization experiments have shown the possibility of ion beam forming in the current range from 40 to 800 mu A.
- ПубликацияОткрытый доступМетод расчета пространственного разрешения диагностики зондирования пучком тяжелых ионов токамака Т-15МД(2025) Аммосов, Я. М.; Крохалев, О. Д.; Елисеев, Л. Г.; Саранча, Г. А.; Мельников, А. В.; Мельников, Александр ВладимировичЗондирование плазмы пучком тяжелых ионов (ЗПТИ) – уникальная диагностика, позволяющая независимо и одновременно измерять электрический потенциал плазмы φ, его колебания φ˜, а также колебания электронной плотности n˜e и полоидального магнитного поля B˜pol в горячей области плазмы. В работе приводится метод расчета пространственного разрешения проектируемой диагностики ЗПТИ для токамака Т-15МД. Исследована зависимость размера области измерения от ширины входных щелей в энергетический анализатор.
- ПубликацияОткрытый доступПолучение длиннофокусных ионных пучков на высоковольтном стенде диагностики плазмы пучком тяжелых ионов токамака Т-15МД(2025) Вадимов, Н. А.; Виницкий, Е. А.; Елисеев, Л. Г.; Харчев, Н. К.; Мельников, А. В.; Саранча, Г. А.; Драбинский, М. А.; Мельников, Александр Владимирович; Виницкий, Егор АлександровичИзучены свойства диагностического пучка ионов таллия (Tl+) в зависимости от параметров ионно-оптической системы инжектора диагностики плазмы зондированием пучком тяжелых ионов. Показана возможность получения как квазипараллельных, так и сходящихся пучков с фокусным расстоянием более 4 м, необходимых для создания диагностики для токамака Т-15МД. Проведено сравнение экспериментальных данных с результатами компьютерного моделирования пучка в инжекторе.
- ПубликацияТолько метаданныеDensity profile reconstruction using HIBP in ECRH plasmas in the TJ-II stellarator(2019) Khabanov, Ph. O.; Eliseev, L. G.; Drabinskiy, M. A.; Hidalgo, C.; Melnikov, A. V.; Мельников, Александр ВладимировичHeavy Ion Beam Probing (HIBP) is a unique tool for plasma potential measurements. In the TJ-II stellarator (CIEMAT, Madrid, Spain) HIBP is capable to move the sample volume (SV) from Low Field Side (LFS) of a plasma column through the plasma center to High Field Side (HFS), so the time evolution of plasma potential phi and secondary beam total current I-tot radial profiles can be obtained during one shot. I-tot is proportional to the plasma density n(e) at the SV, it is affected by attenuation factors along the beam trajectory. The work shows the method for the n(e) radial profile reconstruction from HIBP I-tot signal. Using the method, for the first time n(e) radial profiles are reconstructed from HIBP I-tot signal in TJ-II regimes with electron cyclotron resonance heating (ECRH) and the line-averaged electron density (n) over bare up to 0.8 . 10(19) m(-3). Reconstructed ne(rho) profiles are consistent with Thomson scattering data.
- ПубликацияТолько метаданные3D structure of density fluctuations in the T-10 tokamak and new approach for current profile estimation(2019) Vershkov, V. A.; Buldakov, M. A.; Subbotin, G. F.; Shelukhin, D. A.; Melnikov, A. V.; Мельников, Александр ВладимировичThe paper is focused on the new systematic measurements of the 3D spatial distributions of the amplitudes, the radial correlation lengths and the long-range correlations along the magnetic field lines for the different turbulence types. The density fluctuations were measured by the heterodyne correlation reflectometry (CR) using the plasma probing with ordinary mode. CR data was supported by recent experiments with the measurements of the perturbation properties using an heavy ion beam probe (HIBP). The new reflectometer antenna array in T-10 tokamak consists of sets of horns distributed at four places toroidally and poloidally over the torus. The experiments confirmed previously found strong poloidal asymmetry of the amplitude for the broadband (BB) and quasi-coherent (QC) fluctuations. It was found that amplitude of density fluctuations is uniform poloidally for the stochastic low frequency (SLF) fluctuations. The radial correlation were measured at four poloidal angles to reveal the poloidal dependence of the radial correlation length for the different fluctuation types. The significant decrease of the radial correlation lengths towards the high magnetic field side was observed for the QC and the SLF fluctuations. The long-range correlations along the field lines were measured by the reflectometers in two cross-sections separated by 1/4 of the torus. The reflectometers had the same probing frequency thus provide reflection from the same magnetic surface. The measurements were carried out at the low and the high field sides with two currents and two magnetic configurations with simultaneous reversal of the toroidal field and plasma current. The positions of the resonance radius were calculated also using 3D tracing of the magnetic field line and demonstrated good agreement with experiment ones. These results allow to propose the new approach for the current profile measurements in tokamaks.
- ПубликацияТолько метаданныеConceptual design of the heavy ion beam probe diagnostic for the T-15MD tokamak(2019) Drabinskiy, M. A.; Khabanov, P. O.; Eliseev, L. G.; Kharchev, N. K.; Melnikov, A. V.; Мельников, Александр Владимирович© 2019 IOP Publishing Ltd and Sissa Medialab.The conceptual design of the heavy ion beam probe (HIBP) for T-15MD tokamak (R = 1.5 m, a = 0.67 m, Bt = 2 T, Ipl = 2 MA) is presented. The location of the HIBP injection and detection points is chosen based on the probing beam trajectory calculations. Observation area covers the whole radial interval 0 < r < a for Bt = 1 T, Ipl = 1 MA with the beam energy Eb <260 keV for Tl+ probing ions. It allows to measure two-dimensional maps of plasma parameters in an area which covers a large fraction in the upper right quarter of the plasma cross-section. In order to provide the measurements in a wide range of plasma density, high intensity long-focusing probing beam is needed. To develop such a beam a high voltage test bench is designed. It will allow to study the ion-optics system of the HIBP injector and the properties of the thermionic emitters and their lifetime.
- ПубликацияТолько метаданныеPreface(2019) Melnikov, A. V.; Мельников, Александр Владимирович