Plasma Physics Reports最新文献

Ion cyclotron resonance heating is considered as one of the methods of additional heating of plasma and production of the non-inductive current in the T-15MD tokamak. To transfer the maximum power to the plasma, it is needed to know impedance of an antenna–plasma system, to match it with impedance of an RF power generator and its transmission line. The work is devoted to the development of a code for the calculation of antenna impedance of the ICR heating system of plasma in toroidal magnetic traps. To find impedance of the antenna–plasma system in the simplified geometry of antenna consisting of conductive plates, the wave equation is solved in the “cold” plasma approximation, and the spectrum of the RF power emitted by antenna is calculated. The dependences of the impedance of the antenna–plasma system on distances between antenna and the Faraday screen and between the Faraday screen and the plasma are obtained for the geometry of the T-15MD tokamak. Two-dimensional distribution of electric field of a wave in the plasma is obtained.

A new method is proposed for measuring the electron plasma temperature at the GOL-NB facility. The method is based on measuring the ratio between the intensities of the spectral lines emitted by the fast atoms injected into the plasma. The beams of fast hydrogen atoms used for heating the plasma at the GOL-NB facility contain not only atoms with a full energy (E) but also atoms with fractional energies (E/2, E/3, E/18) that appear as a result of the dissociation of the H(_{2}^{ + }), H(_{3}^{ + }), and H₂O⁺ molecular ions. The spectral lines of the beam components with these energies (and, in particular, the hydrogen H_α line) can be resolved due to the Doppler shift caused by the difference between the atom speeds. For atoms with low energy, the excitation that leads to the photon emission occurs only due to their collisions with thermal electrons, while for atoms with high energy, a sufficient deposition into their excitation is given by their collisions with the plasma ions. This is why the ratio between the intensities of the lines of different beam components depends on the plasma electron temperature, and thus, it can be used to measure this temperature. At the beam energy of 24 keV, the proposed method can be used to measure the electron temperature in the range of up to 40 eV, which is of interest for the current experiments conducted at the GOL-NB facility. Note that measurement of the electron temperature higher than 20 eV requires that the ratio between the spectral line intensities be measured with an accuracy of the order of one percent, and that the attenuation of the neutral beam that passes through the plasma be measured with the same accuracy. The proposed method can be used at other fusion facilities that use fast hydrogen atom injection to measure the temperature of the edge plasma.

The influence of dust grains on soliton reflection in the presence of trapped electrons in an inhomogeneous plasma is investigated. We have considered a plasma model having ions, trapped electrons, and negatively charged dust particles. Here, the reductive perturbation theory (RPT) is employed to obtain the modified Korteweg–de Vries (m-KdV) equation. The solution of m-KdV equation indicates the solitary wave solution in the inhomogeneous plasma system. The solitary wave solution signifies the various effects of dust particles in inhomogeneous plasma. We have also discussed the different modes of soliton propagations during soliton reflection in the presence of inhomogeneity density gradients.

The effect of the dust grain flows on a spatial dusty structure in a stratum of a glow discharge in two inert gases (neon and argon) in a weak magnetic field was studied. The discharge parameters were determined that are necessary for the creation of three-dimensional dusty structures made from dust grains of the same size in both gases in a magnetic field. The dependences were obtained of the angular velocities of the dusty structures in the two gases on the magnetic field and on the gas pressure. The rotation speeds of the dust grains in the magnetic field were used to compare the ion fluxes acting on the dust formations.

A microwave discharge inside of a methane bubble in boiling water is modeled in a 0D approximation taking into account the change in the size of the plasma bubble. The process of quenching the reaction products after the bubble detaches from the electrode surface is also simulated. The working pressure is 1 atm. It is shown that the main reaction products are H₂, CO₂, and CO. The ratio of CO₂ and CO concentrations depends on the ratio of the initial flows of water vapor and methane. The calculated concentrations of the main decomposition products of methane and water are in good agreement with experimental data.

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 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.

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. 71 568 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.

In studies of impurity transport in quasi-stationary hot plasma, the initial kinetic equation and the diffusive-convective transport model take into account ionization and recombination as “sources and sinks” of particles. Due to the incompatible representation of the radial dynamics and charge kinetics of impurity charge states, this approach and the results obtained appear to be out of system. The basis for their systematic criticism is the ideas of the theory of random processes proposed by M.A. Leontovich in 1935 as a theoretical alternative to the gas-kinetic equation. In this case, the charge-radial transport of an impurity in a quasi-stationary plasma is defined as a syncretic vector random Markov process of charge state transport. Its coupling (ergodicity) in a two-dimensional Markov system excludes “sources and sinks” from it in principle, and the relaxation convergence is directed to the formation of equilibrium invariant density profiles. The impurity equilibrium and density profiles are specified by a system of invariant functions that provide analysis of any types of density profiles observed in experiments. Modeling of radial profiles of helium, boron and carbon impurities allows us to find variants of their transformation from accumulation in the center to concentration near the plasma edge, transport coefficients and systematic connection with plasma parameters.

The results of flyer acceleration up to the velocity of 10 km/s at the Angara-5-1 facility at the current of 5 MA by the magnetic field pressure are presented. 1D and 2D simulation of aluminum flyer acceleration is performed. The simulation results agree with each other and with the experimental data.