Plasma Physics Reports最新文献

The results of the study of the dynamics of an arc discharge burning in the electric arc chamber of an alternating current plasma torch with the power of up to 10 kW are presented. The measurements have been carried out using graphite and tungsten electrode tips at the atmospheric pressure in the following ranges of plasma-forming gas flow rates: H₂ up to 0.08 g/s and a mixture of H₂ + CH₄ up to 0.1 g/s. Characteristic stages of the discharge development have been obtained, among which contracted, diffuse with the formation of a plasma plume and transient types of the arc discharge have been observed.

The theory of large-scale flows of rotating incompressible totally ionized plasma is developed taking into account the Hall effect in the beta-plane approximation for the Coriolis force. In the process, the Coriolis force is taken into account for each plasma component. In the beta-plane approximation, the Coriolis force expressed in the local Cartesian coordinate system attached to a fixed point on the sphere becomes inhomogeneous and, as a consequence, leads to the beta-effect for both the equation of motion and the equation governing the electromagnetic field. Linear flows are analyzed in the quasi-two-dimensional approximation. It is demonstrated that a new type of flows, an electron Rossby wave, appears in a rotating totally ionized plasma on a sphere in addition to the hydrodynamic Rossby waves of a neutral fluid. The inhomogeneity of the vertical component of the angular velocity of rotation on a sphere plays the role of the restoring force for such waves.

The most interesting new results are discussed that were presented at the LII International Zvenigorod Conference on Plasma Physics and Controlled Fusion, which was held in Zvenigorod, Moscow region, on March 17–21, 2025. The achievements in the main fields of research in plasma physics in Russia are analyzed and compared with those obtained in foreign scientific centers.

Studies of plasma produced and confined in quasi-stationary L-2 and L-2M stellarators are presented. In these facilities, plasma was produced by the non-inductive electron cyclotron resonance (ECR) microwave heating in the power range of P = 0.05–1 MW. The radial structure of the near-separatrix region (the relative radius of 0.8–1) and fluctuations of plasma parameters in the mode without changing macroparameters are considered. Fluctuations of the near-wall plasma parameters—density, electric potential, and magnetic field—and their evolution during discharges are analyzed. The structure of the electric field and heat flux in the near-wall plasma measured by Langmuir probes is analyzed. The relation between changes in fluctuating plasma parameters and possible small-scale instabilities is analyzed. The mechanisms of the development of permutation, peeling and temperature gradient edge instabilities are considered. A comparison is made between the simulation of the energy transfer in plasma using neoclassical models taking into account anomalous energy losses and that based on canonical pressure profiles. The possibility of using a quasi-stationary stellarator as a source of plasma flows with three-dimensional geometry for materials science is considered.

The effect of the electron relativistic beam (REB) current on the operation mode of a plasma relativistic microwave generator with inverse geometry (where a tubular REB is located around the plasma, not inside, as in earlier works with conventional geometry) and its radiation characteristics have been studied using the numerical simulation method (the PIC method). It is shown that an increase in the REB currents does not lead to an increase in the energy of the output microwave pulse of a plasma relativistic generator but to its decrease for a large range of plasma densities up to 7 × 10¹² cm^–3. When a certain threshold of the REB current is exceeded, the electron energy distribution function of REB changes its shape, the transverse plasma density profile degrades, an ion background is formed, and, as a consequence, shortening of the microwave pulse and a change in the generation mode occur.

The development of lightning plasma was analyzed for the low-current stage, during the time intervals between the passage of the stepped leader stroke and the return stroke, as well as between the return stroke and the dart leader of the subsequent lightning stroke. It was shown that the equilibration time in the analyzed plasma is short compared to the duration of the slow lightening stages. Therefore, in the plasma of the conducting channel of lightning during the slow stage of its development, a local thermodynamic equilibrium is established, and the plasma temperature in each point is the same for electrons and atoms. According to a gas–dynamic model, the plasma decay time after the return stroke (1 ms) is short compared to the duration of the slow stage (50 ms). Therefore, an external electric field is necessary to maintain the plasma during the slow stage, which generates a weak electric current that stabilizes the plasma in the conducting channel. Taking into account the results of numerical models for the relaxation of the plasma of the return stroke, parameters of heat transfer were determined, which are connected to the thermal conductivity of the plasma inside the conducting channel, mainly due to the transfer of dissociative excitation and the thermal conductivity of electrons. At the boundary of the conducting channel of the lightning, the heat transfer occurs as a result of the convection of surrounding air, which leads to the formation of “tongues” and vortices approximately 10 cm in size. The convection leads to a complete renewal of hot air in the conducting channel with cold air at a temperature of 7 kK over a period of about 40 ms.

An unusual glow discharge has been discovered in a Xe+Cs mixture. Its burning voltage is several times lower and the current density is 1–2 orders higher than the normal voltage and current of a regular glow discharge in pure xenon and cesium, respectively. These discharges occur in cesium lighting lamps of a pulse-periodic discharge when they are heated by the alternating voltage before applying high-current operating pulses at a xenon pressure of 20 Torr and a wide range of cesium pressures (10^–6–1) Torr. The most probable origin of their occurrence is photoemission from W–Th–Cs structures on the electrodes under the impact of intense UV radiation of the cathode layer.

The results of experiments on the use of microwave discharge plasma supported by microwave radiation of a pulsed (6 ms) gyrotron for the transfer of matter from a metallic silver nanopowder to the surface of a dielectric ABS (acrylonitrile butadiene styrene) plastic target are presented. The experiments are carried out at atmospheric and reduced pressure (up to 50 Torr) of air at a microwave radiation power density from 1.25 to 12 kW/cm². The spatial structures of microwave discharge plasma propagating near a quartz substrate with a silver nanopowder layer are studied. It is determined that the discharge can have at least three types of the spatial structure: (a) localized microwave discharge at the points of the discharge initiation; (b) microwave discharge propagating through the quartz substrate; (c) microwave discharge propagating along the quartz substrate. The metal layer deposited on the plastic surface is characterized using electron microscopy.

A review of theoretical studies of dusty plasma in the atmospheres of planets of the solar system carried out at the Space Research Institute of the Russian Academy of Sciences is given. Special attention is paid to physical processes related to noctilucent clouds, polar mesosphere summer echoes, dust-acoustic perturbations in the Earth’s atmosphere, clouds in the ionosphere of Mars, and Schumann resonances (SR). It is noted that intense studies of the plasma-dust processes in the atmospheres of planets can currently be carried out for the Earth and Mars. Studying the corresponding process in the atmospheres of other planets of the solar system requires additional knowledge on the objects that can be gained only in the course of future space missions.

Experimental results characterizing the dynamics of the electrically exploding platinum wires without and with insulating coatings are presented. The insulating coatings substantially enhance the energy deposition with the overheating coefficients increasing from 0.5 for exploding bare platinum wires to 1.3 for exploding coated platinum wires with 2 cm in length. Although the homogeneous vaporized platinum wires can be realized in the exploding coated platinum wires, the exploding products exhibits a strong stochastic behavior. Most of the electrically exploding platinum wires produce inhomogeneous structures in energy deposition. Shortening the wire length further increases the specific energy deposition. The total deposited energy is high enough to vaporize the entire wire, while only a part of the wire is transformed into gaseous state. The percentage of vaporization increases almost linearly with the axial electrical field. With decrease of the wire length from 2 to 0.5 cm, the specific energy deposition increases from 2.6 to 14.9 eV/atom, and the percentage of vaporization improves from 52 to 92%.