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Лисица, Валерий Степанович

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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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Валерий Степанович

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Absorption of ultrashort electromagnetic pulses in plasma with inhomogeneous distribution of density and temperature
(2020) Astapenko, ValeriyA.; Sakhno, Sergey, V.; Lisitsa, ValeryS.; Лисица, Валерий Степанович
The analysis of influence of the inhomogeneous distribution of temperature and density of atoms on the probability of absorption of ultrashort electromagnetic pulses in plasma is carried out. A specific example of divertor plasma of tokamaks and absorption in the Lyman series (at the Ly-alpha line) is considered. It is shown that the absorption probability may exceed relative populations of excited levels in divertor plasma by several orders of magnitude. The influence of the pulse duration on the probability of excitation of an atomic level is considered. The results suggest a possibility of a sharp increase in a fluorescence signal under the action of an ultrashort pulse.
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Stark-Zeeman and Blokhintsev Spectra of Rydberg Atoms
(2020) Letunov, A. Y.; Lisitsa, V. S.; Лисица, Валерий Степанович
The problem of Rydberg atomic spectra in crossed electric F and magnetic B fields (combined Stark-Zeeman effects), as well as an oscillating electric field are under consideration. The main problem is the great array of radiative transitions between the Rydberg atomic states. The different versions of semiclassical approaches are applied for the solution of the problem. New approximate selection rules are established to simplify the matrix elements of radiative transitions, making it possible to reduce the complex expressions of Gordon's hypergeometric series to the trivial trigonometric functions. Simple analytical formulas for the dipole matrix elements of a Rydberg hydrogen-like atom in external crossed electric and magnetic fields for H-n alpha are obtained. The specific calculations are presented for n = 10 to 9 transition both for parallel and perpendicular orientations of F-B fields. The result of Blokhintsev for a single Stark component in oscillating field is generalized for the array of radiative transitions between Rydberg atomic states. Such spectra with large values of modulation index are compared with static ones.
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Simulation of passive charge exchange signals of hydrogenlike beryllium ions for cxrs edge diagnostics in iter
(2020) Sdvizhenskii, P. A.; Levashova, M. G.; Neverov, V. S.; Romazanov, Y. A.; Kukushkin, A. B.; Lisitsa, V. S.; Кукушкин, Александр Борисович; Лисица, Валерий Степанович
© 2020 National Research Center Kurchatov Institute. All rights reserved.For one of the divertor's operation scenarios in ITER, the background radiation from passive charge exchange was calculated for one of the beryllium (Be IV) spectral lines used for Charge eXchange Recombination Spectroscopy (CXRS) diagnostics. The contribution of the charge exchange of beryllium ions Be V on neutral deuterium atoms in the ground and first excited states is calculated. The cross sections for the charge exchange reaction calculated by the numerical code ARSENY and other codes are used. The data from the ITER edge plasma modeling database is used based on the SOLPS numerical code: Calculations of the kinetics of deuterium recycling by the EIRENE code and the erosion of the beryllium first wall by the ERO2.0 code.
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Thomson scattering in plasmas: Theory generalization for ultrashort laser pulse effects
(2020) Astapenko, V. A.; Khramov, E. S.; Rosmej, F. B.; Lisitsa, V. S.; Лисица, Валерий Степанович
© 2020 Author(s).The standard approach to calculate the Thomson scattering probability is reconsidered for the case of ultrashort incident laser pulses (USLPs). We established a new model for the interaction of USLP with plasmas that is based on Fermi's equivalent photon conception to calculate the spectral-angular differential Thomson scattering probability. The simulations demonstrate that the scattering probability for USLP is a non-monotonic function of pulse duration in contrast to the standard long-pulse model showing linear dependence. An analytical approach is developed to study the nonlinear behavior of the scattering probability as a function of pulse duration and other parameters.
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Spectra of a rydberg atom in crossed electric and magnetic fields
(2020) Letunov, A.; Lisitsa, V.; Лисица, Валерий Степанович
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Contemporary spectroscopic studies of astrophysical and laboratory plasmas frequently deal with extremely large values of principle quantum numbers of atomic systems. These atomic states are very sensitive to electric and magnetic fields of the surrounding medium. While interpreting the spectra of such excited atomic systems, one faces the problem of a huge array of radiative transitions between highly excited atomic levels. Moreover, external electric and magnetic fields significantly complicate the problem because of the absence of standard selection rules typical for the spherical quantization. The analytical expression in the parabolic representation for dipole matrix elements obtained by Gordon contains hyper-geometric series and it has a very complex structure. The matrix elements that involve the presence of electric and magnetic fields are calculated while using a representation closely related to the parabolic quantization on two different axes. This matrix element depends in a complex way on the transition probabilities in the parabolic coordinate system (Gordon's formulas) and the Wigner d-functions. This circumstance leads to even greater computational difficulties. A method of simplification of these complicated expressions for transition probabilities is demonstrated. The semiclassical approximation for coordinate matrix elements (Gulayev) and recurrence properties of the Wigner d-functions are used. The Hnβ line is under consideration. Specific calculations for the transition 10-8 in the case of parallel and perpendicular fields are presented.
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Analysis of accuracy of measuring the flux density of all hydrogen isotopes from first wall to plasma using the H-alpha diagnostics in ITER АНАЛИЗ ТОЧНОСТИ ИЗМЕРЕНИЯ ПЛОТНОСТИ ПОТОКА ВСЕХ ИЗОТОПОВ ВОДОРОДА С ПЕРВОИ СТЕНКИ В ПЛАЗМУ С ПОМОЩЬЮ Н-АЛЬФА-ДИАГНОСТИКИ В ИТЭР
(2019) Neverov, V. S.; Shurygin, V. A.; Alekseev, A. G.; Kukushkin, A. B.; Lisitsa, V. S.; Кукушкин, Александр Борисович; Лисица, Валерий Степанович
© 2019 National Research Center Kurchatov Institute. All rights reserved.The results of the analysis of the accuracy of measuring the flux density of all hydrogen isotopes from the first wall of the main vacuum chamber to the ITER tokamak plasma using the high-resolution spectroscopy of Balmer-alpha lines of hydrogen isotopes (H-alpha diagnostics) are presented. Under the conditions of the expected high background radiation generated by the divertor stray light and the absence of the possibility of using the optical dumps in ITER, a differential measurement scheme is necessary, which uses the spatial variation of the coefficient of the light reflection from the natural landscape of the first wall. The measurement accuracy analysis is carried out with the help of the method of synthetic diagnostics, which uses the results of the predictive numerical modeling of different modes of hydrogen recycling for simulation of the expected diagnostic signals and determination of the sought-for parameters by solving an inverse problem.
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Ballistic model of recycling of atomic and molecular hydrogen and its application to the ITER main chamber
(2021) Neverov, V. S.; Shurygin, V. A.; Kukushkin, A. B.; Kukushkin, A. S.; Lisitsa, V. S.; Pshenov, A. A.; Кукушкин, Александр Борисович; Лисица, Валерий Степанович
© 2021 IOP Publishing LtdA simple, computationally efficient 1D model is suggested for the recycling of atomic and molecular hydrogen between the main chamber first wall (FW) of a tokamak and the peripheral plasma. The model is based on iteratively solving the kinetic equation for the 1D velocity distribution function (VDF) of hydrogen neutral atoms in the projection of velocity on the direction normal to the FW. The model results in a fast-converging routine due to the domination of the contribution to the VDF from long-distance, ballistic flights of the neutral atoms produced by the charge exchange of colder atoms with hotter plasma ions. The proposed modification of the ballistic model (BM) enhances its original version along the following lines: the account of the inelastic reflections of the neutral atoms from the wall; parameterisation of the boundary condition for the VDF of the atoms produced by the reflection of ions from the wall with immediate recombination, without capture in the wall and thermalisation there; extension to a mixture of hydrogen isotopes; elaboration of algorithms for speeding up computation on graphical processing units. The complete set of equations of the BM is published for the first time. The model is verified by comparison with the EIRENE code simulations of the VDF of neutral atoms and molecules in the scrape-off-layer around mid-plane for typical conditions of ITER operation. The applicability of the BM to the synthetic diagnostics developed for the H-alpha high-resolution spectroscopy is demonstrated. That is, the simple 1D model reproduces reasonably well the 1D projection of the data computed with the 3D Monte-Carlo code on a 2D plasma background.
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ТЕРМОДИНАМИЧЕСКАЯ НЕРАВНОВЕСНОСТЬ РЕЦИКЛИНГА ВОДОРОДА В ПРИСТЕНОЧНОЙ ПЛАЗМЕ ТОКАМАКА И ЕЕ ВЛИЯНИЕ НА ПЕРЕЗАРЯДОЧНУЮ СПЕКТРОСКОПИЮ В ИТЭР
(НИЯУ МИФИ, 2023) КУКУШКИН, А. Б.; КУКУШКИН, А. С.; ЛЕВАШОВА, М. Г.; ЛИСИЦА, В. С.; НЕВЕРОВ, В. С.; ПШЕНОВ, А. А.; СДВИЖЕНСКИЙ, П. А.; ТОЛСТИХИНА, И. Ю.; ХУСНУТДИНОВ, Р. И.; СЕРОВ, С. В.; ТУГАРИНОВ, С. Н.; Хуснутдинов, Радмир Ильдарович; Кукушкин, Александр Борисович; Лисица, Валерий Степанович
Термодинамическая неравновесность рециклинга изотопов водорода в пристеночной плазме токамака состоит в существенном отклонении функции распределения по скоростям (ФРС) нейтральных атомов изотопов водорода от однотемпературной максвелловской ФРС. Такое отклонение впервые обнаружено в спектроскопических измерениях излучения плазмы в линиях бальмеровской серии водорода и дейтерия в токамаке Т-3 [1]. В настоящей работе проанализировано влияние указанной термодинамическая неравновесности на пассивный сигнал перезарядочной спектроскопии (CXRS-диагностики) периферийной плазмы в токамаках на примере ожидаемых условий в токамаке ИТЭР.
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Saturation Effect Produced by Laser Pulses: Karplus–Schwinger Approach versus Bloch Solution
(2022) Astapenko, V.; Lisitsa, V.; Лисица, Валерий Степанович
The saturation effect during the excitation of a two-level system by laser pulses is investigated in the framework of two approaches: excitation probability based on KarplusвЂ“Schwinger spectral profile and exact solution of Bloch equations. Simple analytical expression for the excitation probability by exponential pulse is derived. The excitation spectra obtained using this expression were compared with the result of solving the Bloch equations for various values of the pulse duration and the Rabi frequency, which describes the strength of the electromagnetic interaction. It is shown that in the case of long pulses, there is a satisfactory correspondence between the two approaches, but in short-pulse limit and strong saturation, the probability description based on KarplusвЂ“Schwinger spectral profile and perturbation theory does not provide satisfactory results.
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Algorithm of calculating the passive signal of tokamak edge plasma for CXRS diagnostics
(2019) Sdvizhenskii, P. A.; Levashova, M. G.; Neverov, V. S.; Serov, S. V.; Kukushkin, A. B.; Lisitsa, V. S.; Кукушкин, Александр Борисович; Лисица, Валерий Степанович