Nikita Efimov

For codes that simulate plasma–surface interactions, data on sputtering and particle reflection are required. Programs based on the binary collision approximation, such as SDTrimSP, are often used to obtain these data. This paper describes an auxiliary code developed to compute parameters of sputtered and scattered particles using SDTrimSP. The code can be used to run SDTrimSP and to process its output, including parameterization of sputtering yields and angular distributions of emitted particles as functions of incidence angle and initial energy. A comparison is given of methods for generating particle parameters with prescribed characteristic distributions: approximations by Legendre polynomials and a “butterfly”-type distribution. The applicability of representing the ion distribution over solid angle as the product of azimuthal and polar parts is also investigated. It is shown that Legendre polynomials better describe the obtained dependence of the sputtered particle yield on polar angle than the butterfly distributions. The results will be used in the development of a plasma–surface interaction module for a Monte Carlo code under development, intended to simulate impurity and working-gas transport in fusion devices.

This work is devoted to the development and testing of a pulsed power supply system for magnetic coils of the MEPhIST-0 educational and research tokamak, including capacitor banks, devices for their automated charging, state monitoring, and synchronized switching to toroidal and poloidal field coils and to the central solenoid, as well as protection systems. The technical aspects of the developed system are considered in detail from the standpoint of simplicity, scalability, fault tolerance, maintainability, and the possibility of independent modification. Implemented solutions, including basic electrical circuits and developed boards and modules, can be useful in electrophysical installations with similar parameters and tasks.

A method for calculating sputtering of the tokamak first wall by fast charge-exchange neutral atoms of hydrogen isotopes in the near-wall plasma has been proposed. The application of the method has been shown by the example of sputtering of the assumed first-wall materials under the near-wall plasma conditions in the ITER tokamak. Using the BM1D2V code based on the ballistic model of hydrogen recycling kinetics in the tokamak main vacuum chamber, the velocity distribution function (VDF) of neutral atoms and molecules of hydrogen isotopes in the near-wall plasma has been calculated. Using the calculated VDFs, the sputtering rate of beryllium, tungsten, and boron from the surface of the first wall of the tokamak vacuum chamber in a typical ITER divertor operating mode has been estimated. The reflection coefficients of atoms of hydrogen isotopes from the first wall used in the ballistic model and the sputtering coefficients have been calculated using the SDTrimSP code.

In this work, the profiles of craters obtained by the irradiation of a picosecond laser with a wavelength of 1064 nm and energy density in the range of 0.4–7.0 J/cm² of tungsten films were measured using energy-dispersive X-ray spectroscopy, as well as a contact profilometry. The presence of several mechanisms of surface erosion at given irradiation parameters is shown. The influence of the craters shape on the signal of laser-assisted quadrupole mass spectrometry during irradiation of deuterium-containing tungsten films is analyzed.

The paper compares the laser-assisted quadrupole mass spectrometry for two laser pulses (15 ns and 80 ps) for W-D films and Ti–V alloy with deuterium. A technique for the production of samples with high concentrations of trapped deuterium, which makes it possible to obtain a good signal repeatability on a quadrupole mass spectrometer for several laser shots, is presented, which can be used to align a diagnostic laser system. The experimental dependence of the total deuterium yield from the studied materials on the energy density is obtained. The high sensitivity of the technique, as well as a weak dependence on the laser pulse duration, is demonstrated. A significant change in the deuterium concentration in the near-surface layer of the tungsten film during contact with the atmosphere is noted.

The article is devoted to the calculation of equilibrium configurations of the MEPHIST-0 tokamak plasma with a poloidal magnetic system taking into account the part responsible for compensating the magnetic field of the central solenoid using the DINA plasma physics code. The parameters of the poloidal magnetic system necessary for the formation of initial equilibrium after the discharge breakdown are obtained. The results of calibration experiments without taking into account the vacuum chamber using a pulsed current source are presented, on the basis of which the dynamic problem of plasma equilibrium calculation is formulated. The simulation results are compared with the experimental data, and the influence of the chamber on the results is considered.