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 метаданныеQuasi-coherent mode evolution in discharges with positive radial electric field at the T-10 tokamak(2021) Drabinskiy, M. A.; Eliseev, L. G.; Khabanov, P. O.; Kharchev, N. K.; Melnikov, A. V/.; Мельников, Александр Владимирович© 2021 Institute of Physics Publishing. All rights reserved.The effect of the high-power ECRH on the quasi-coherent (QC) mode in the plasma of the T-10 tokamak with the magnetic field B= 2.2 T, plasma current = 230 kA and chordaveraged electron density ≈ 1·1019m-3is discussed. The most pronounced changes appear in the core plasma region with r < 0.5a. For the ECRH power PECRH= 2.2 MW causing the appearance of the positive radial electric field ErEC= +20 V/cm (in the OH stage, the occurring field is ErOH= -75 V/cm), the mean frequency of the QC-mode gradually decreases from fQCOH= 80-100 kHz (in the OH stage) to fQCEC= 20 kHz, and its frequency spread ΔfQCdecreases from ΔfQCOH= ±50 kHz to ΔfQCEC= ±10 kHz. For the ECRH power PECRH= 1.7 MW and weak negative radial electric field (ErEC= -20 V/cm), the mean frequency decreases to fQCEC= 40 kHz, and the frequency spread becomes ΔfQCEC= ±30 kHz. After the ECRH-induced drop, the QC-mode mean frequency increases with increasing line-averaged density.
- ПубликацияТолько метаданныеDesign of inductive sensors and data acquisition system for diagnostics of magnetohydrodynamic instabilities on the T-15MD tokamak(2019) Sushkov, A. V.; Belov, A. M.; Igonkina, G. B.; Kachkin, A. G.; Melnikov, A. V.; Мельников, Александр Владимирович© 2018 Magnetic diagnostics plays an important role in tokamak operation. Magnetic data are used for the real-time control of plasma current, shape and position and for post-discharge analysis of magnetohydrodynamic (MHD) plasma instabilities and equilibrium reconstruction. The magnetic diagnostic of the T-15MD will consist of more than 350 inductive sensors of various types. Location and number of sensors is determined by the measured physical value. The data acquisition system must simultaneously provide both the real-time data transfer of some sensors to the control loop and all sensors data storage for subsequent analysis. The requirements for the data acquisition depend on the data destination. For the data transferred to the control loop is sufficient to have a sampling rate up to 10 kHz, but this data must be transferred and processed in real-time mode. At the same time, for the study of fast processes (disruptions, tearing modes, Alfvén eigenmodes), sensor signals should be acquired with a sampling rate from 100 kHz to 2 MHz and transferred to the database in about 3 min after discharge. The article describes the construction and location of inductive sensors, as well as the peculiarity of the magnetic diagnostics data acquisition system.
- ПубликацияТолько метаданныеStudies of poloidal rotation of plasma density turbulence with HIBP in the T-10 tokamak(2019) Drabinskiy, M. A.; Eliseev, L. G.; Khabanov, P. O.; Kharchev, N. K.; Melnikov, A. V.; Мельников, Александр Владимирович© EPS 2019. All rights reserved.Plasma density turbulence (f < 250 kHz) study using 5-slits HIBP in ohmic T-10 discharges (Bt = 2.2-2.48 T, Ipl = 200-230 kA, ne = 1-3×1019 m-3) have shown the complex frequency and spatial structure. It was shown that SLF and LFQC modes have features of solitary bursts with poloidal wavelengths comparable to correlation lengths (?cor SLF ˜ 4 cm, ?cor LFQC ˜ 5 cm, ?SLF < 20 cm, ?LFQC < 7 cm). LFQC always rotates to the EDD direction, while SLF may also rotate to the IDD direction. Study of these differences is a topic for further research.
- ПубликацияТолько метаданныеTwo-Dimensional Distribution of Plasma Electric Potential in the T-10 Tokamak(2023) Ammosov, Y. M.; Khabanov, F. O.; Drabinskiy, M. A.; Melnikov, A. V.; Мельников, Александр Владимирович
- ПубликацияТолько метаданныеStability analysis of TJ-II stellarator NBI driven Alfven eigenmodes in ECRH and ECCD experiments(2021) Cappa, A.; Varela, J.; Bruna, D. L.; Ascasibar, E.; Melnikov, A. V.; Мельников, Александр ВладимировичIn this paper, we analyze the impact of electron cyclotron resonance heating and electron cyclotron current drive on the Alfvenic instabilities driven by neutral beam injection observed in the TJ-II stellarator. An MHD stability analysis of driven Alfven eigenmodes compatible with the experimental plasma parameters is carried out in order to compare with the data provided by magnetic coils, radiation monitors, and heavy ion beam probes. To this end, the vacuum magnetic configuration modified by the different levels of plasma current, the thermal plasma parameters and the fast ion pressure profiles generated by the co-injected neutral beam, are entered in the FAR3d gyro-fluid code in order to follow the linear evolution of the destabilized plasma equilibrium. Linear growth rates and radial location of the dominant predicted modes coincident in frequency with the observed fluctuations are presented. Despite the uncertainties related to the estimation of the rotational transform profile, the code predictions agree within reasonable accuracy with the experimental results.
- ПубликацияТолько метаданныеNegative-Triangularity Magnetic Configurations in T-15MD Tokamak(2021) Gorbun, M. S.; Sychugov, D. Y.; Melnikov, A. V.; Мельников, Александр Владимирович© 2021, Springer Science+Business Media, LLC, part of Springer Nature.The article focuses on a numerical analysis of the projected use of the T-15MD tokamak machine after its physical launch for generating a configuration with negative triangularity of the plasma filament cross section (an inverted D shape) on the installed magnetic field coils. The study is of interest in connection with recent experiments on several tokamaks that have demonstrated a distinct improvement achieved with such operating regimes compared with standard plasma containment configurations.
- 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.
- ПубликацияТолько метаданныеTRANSPORT MODELS FOR PLASMA HEATING WITH SECOND HARMONIC OF ELECTRON-CYCLOTRON FREQUENCY(2022) Dnestrovskij, Yu. N.; Danilov, A. V.; Dnestrovskij, A. Yu.; Lysenko, S. E.; Melnikov, A. V.; Nurgaliev, M. R.; Мельников, Александр Владимирович; Нургалиев, Максим РинатовичThe optical thickness of plasma is often insufficient to absorb completely electromagnetic waves when heated at the second harmonic of the electron-cyclotron frequency. The analysis of experiments in T-10 allowed us to find the criterion of complete absorption and to provide a transport model for complete and incomplete absorption of waves. The conditions for the equivalence of discharges in different tokamaks, as well as in a pair of tokamak-stellarator W7-X, are formulated. For equivalent discharges, calculations using the model for the T-15MD tokamak meet the measurements of electron and ion temperatures in the W7-X in a wide range of plasma densities. The confirmed model is used to analyze future T-15MD pulses.Оптическая толщина плазмы часто недостаточна для полного поглощения электромагнитных волн при нагреве на второй гармонике циклотронной частоты. Анализ экспериментов на установке Т-10 позволил найти критерий полного поглощения и построить транспортную модель для полного и неполного поглощения волн. Сформулированы условия эквивалентности разрядов в разных токамаках, а также в паре токамак-стелларатор W7-X. Для эквивалентных разрядов расчёты с помощью построенной модели для токамака T-15МД совпадают с экспериментальными результатами измерений температур электронов и ионов в установке W7-X в широком диапазоне плотности плазмы. Подтверждённая модель используется для анализа будущих импульсов в установке Т-15МД.
- ПубликацияТолько метаданныеStudy of Alfven eigenmodes with heavy ion beam probing in the TJ-II stellarator(2022) Eliseev, L. G.; Melnikov, A. V.; Lysenko, S. E.; Мельников, Александр Владимирович
- ПубликацияТолько метаданныеModeling of Alfven cascades in the TJ-II stellarator with STELLGAP and AE3D codes(2022) Ghiozzi, A. G.; Mantsinen, M.; Pastells, P.; Spong, D.; Melnikov, A. V.; Мельников, Александр Владимирович