Vol 50, No 8 (2024)

The results of the first gyrokinetic calculations of anomalous heat fluxes in the T-10 tokamak plasma obtained for typical conditions of a discharge No. 71568 with ohmic heating are presented. The calculations have been performed at the Kurchatov Institute Supercomputer Center. The experimentally measured electron density and temperature profiles, ion temperature profiles with a large gradient leading to the so-called ion temperature gradient (ITG) turbulence, and also the profiles of carbon and oxygen impurity densities measured using the charge exchange recombination spectroscopy (CXRS) active diagnostics are used as input data. The “experimental” electron and ion heat fluxes are estimated from the heat balance condition using the ASTRA transport code. The analytical dependence of heat fluxes on the effective plasma charge is presented. Gyrokinetic calculations of anomalous electron and ion heat fluxes are performed for the T-10 tokamak for the first time. The well-known gyrokinetic GENE code is used in the so-called linear and nonlinear approximation with fixed density and temperature gradients taking into account the influence of carbon and oxygen impurities. A linear dependence of heat fluxes on the effective plasma charge is found, and the sensitivity of the results to input parameter errors is investigated. The results of gyrokinetic calculations for the T-10 tokamak are compared with the results obtained for facilities with similar input parameters. A comparison is made of gyrokinetic calculations of heat fluxes performed using the GENE code with the results of calculations by the CONTRA-T code, intended for the self-consistent simulation of low-frequency turbulence and transport processes in tokamaks with a large aspect ratio. Good agreement obtained in the work between the results of transport calculations using the ASTRA, GENE, and CONTRA-T codes based on various transport models for the ohmic discharge of the T-10 tokamak with a circular cross section, provides grounds for the further simulation of transport processes in plasma with additional heating and a more complex cross section shape of the plasma column.

The paper gives a systematic presentation of the Wigner function method (Weyl formalism) for modeling the propagation and absorption of electromagnetic waves in anisotropic and gyrotropic dissipative media with spatial dispersion. A general kinetic equation for the Wigner function (tensor) is formulated, and its asymptotic expansion up to the second order for smoothly inhomogeneous and weakly dissipative media is constructed. As a result, a modification of the method of the kinetic equation for rays is proposed, based on the stochastic description of rays, making it possible to increase the accuracy of numerical modeling of wave problems with strong transverse inhomogeneity of the absorption coefficient without increasing the amount of calculations. The technique developed can be used to describe the propagation, absorption, and scattering of electron-cyclotron waves in high-temperature plasma of magnetic traps for controlled fusion in cases where standard modeling methods do not provide the necessary accuracy.

Deuterium Z-pinch experimental studies [1] were carried out at the Angara-5-1 facility at a current of 2–2.5 MA with 100 ns rise time. Neutron yield in experiments ranged from 5 Å~ 1010 to 8 Å~ 1011 neutrons per pulse. In order to explain experimental results, the two-dimensional MHD calculations were performed taking into account the generation of DD-neutrons using thermonuclear and beam-target mechanisms. MHD calculations of pinch dynamics, carried out taking into account the deuterium density distribution in the gas puff, satisfactory agree with voltage measurements. The neutron yield in the calculations ranges from 4 Å~ 1010 to 1.5 Å~ 1011 depending on the deuterium density and the time delay between the start of gas puff and the moment of generator start-up. The energy of accelerated deuterons, which lead to neutron generation in the beam-target mechanism, is calculated to be from 55 to 900 keV, which is in satisfactory agreement with the estimates obtained [1]. An important difference between neutron generation in a fast gas Z-pinch and neutron generation in a dense plasma focus is that the contributions of thermonuclear and beam-target mechanisms to neutron generation in a fast gas Z-pinch are comparable, whereas in a dense plasma focus the main neutron generation mechanism is the beam-target mechanism.

Selection of dust particles in three-dimensional plasma–dust trap in the electrodeless radio frequency inductive discharge in neon was studied for the first time. The discharge conditions and the discharge chamber design were chosen so that the dust structures of polydisperse quartz particles are created in the resulting dust trap. The structure lengths were of up to 1.5 cm and the number of particles in them was of up to 4000. Statistical analysis of the sizes of trapped particles has shown that under the conditions chosen the average particle size is close to 4 μm, and in a wide range from 0.25 to 1.0 Torr, it weakly depends on neon pressure. It was found that in the three-dimensional dust structure formed, the longitudinal interparticle distance changes in anomalously wide range, as compared to the dust structures formed in plasma of glow discharge. The characteristic size of the trapped particles was estimated based on the vertical balance of forces acting on dust particle. It was shown that, in terms of a number of parameters, the method of particle selection in radio frequency inductive discharge is preferable, as compared to similar method used in glow discharges in strata, and the dust trap applied can be used for studying three-dimensional dusty plasmas in the magnetic field.

We calculate the photorecombination emission intensity, which determines emission from a hot plasma at thermodynamic equilibrium at a noticeable degree of ionization. In the case of air, the contribution of the short-wavelength emission in the range 60–100 nm to the total emission power is about 90%. Above 10 kK, this contribution is temperature-independent.

The breakdown and discharge ignition in discharge tubes with a diameter of about 1 cm and a length of 80 cm in inert gases (neon, argon, krypton, and xenon) at a pressure of about 1 Torr are studied experimentally. The tube is illuminated by radiation from continuous or pulsed light sources in the visible spectrum range. A ramp voltage with a small slope steepness (of about 50 V/s) is applied to the anode of the tube. Previously, the authors established that under these conditions external illumination can increase the breakdown voltage in several times. This effect was explained by the appearance of a charge on the tube wall as a result of photodesorption of electrons from its inner surface. In this work, it is found that charging the wall begins only when the anode potential approaches the breakdown potential measured without illumination. In addition, it is found that during the increase in the voltage on the anode and charging the wall, the anode potential differs from the breakdown potential by a constant and small value (less than 200 V).

The most interesting new results are discussed that were presented at the LI International Zvenigorod Conference on Plasma Physics and Controlled Fusion, held from March 18 to 22, 2024 in Zvenigorod, Moscow region. The achievements in the main fields of research in plasma physics in Russia were analyzed and compared with those obtained abroad.