[en] The interest to the dusty plasma under elevated pressures of ∼1 bar has risen quite recently and was originally connected with studying the possibility of developing energy sources on the basis of ordered plasma-dusty structures. The non-self-sustained discharge controlled by an external 100 keV electron beam appeared to be most suitable for experimental modeling such a plasma. The conditions of dusty structures formation by way of the numerical research of the self-consistent potential of a dusty particle in nitrogen plasma at room and cryogenic temperatures under high gas density were determined. it was shown that there are the conditions for which the interaction parameter of dusty particles became greater than the critical value, the formation of the ordered plasma-dusty structures of the Coulomb crystal type is expected to occur. for the gas temperature lowering down to ₌ 77 K this range became considerably wider. The model for charging dusty particles was developed on the base of the moment method and the theoretical research was carried out to study the process of charging dusty particles. It was shown that the electron temperature in the helium plasma was not disturbed by dusty particles. It was found out that the density of electrons and ions was lower than the equilibrium values up to the distances which were tens and hundreds of times as great as the radius of dusty particles. It was stated that within the drift-diffusion approximation the potential of a dusty particle was close to that within the orbit motion limited approach. In the experiments the dusty plasma was created by the non-self-sustained discharge in Thompspm regime in Ar, He and N₂ gases at atmospheric pressure. The formation of stable dusty plate-like structures, vortices and traveling waves were observed. the height of levitation of the plate-like structures and their evolution was changed with variation of discharge voltage and e-beam current density. To determine the levitation conditions for dusty particles the self-consistent one-dimension modeling of discharge was performed within the non-local of plasma charged particle transport with the electron diffusion taken into account. In our conditions nearly all the applied voltage dropped within the cathode layer. Therefore, an electrical field distribution growing toward the cathode together with the gravity force formed the potential trap for charged dusty particles. (Author)

[en] The process of dust-grain charging in plasmas produced by radioactive decay products or spontaneous fission fragments in air and xenon at high pressures is studied numerically in the hydrodynamic approximation. It is shown that, at sufficiently high rates of gas ionization, the dust grains in air are charged by electrons rather than ions, so that the grain charge in air is comparable to that in electropositive gases. The results of numerical calculations based on a complete model agree well with the experimental data. The time evolution of the grain charge is investigated, and the characteristic time scales on which the grains acquire an electric charge are established. The validity of approximate theories of dust-grain charging in electropositive and electronegative gases at high pressures is examined

[en] The parameter of a terahertz (THz) laser intended for plasma diagnostics in electrodynamic accelerators and tokamaks with a strong magnetic field are discussed. Generation of THz radiation in an ammonia laser under the action of high-power pulsed optical pumping by the radiation of a 10P(32) CO₂ laser is simulated numerically. The main characteristics of the output radiation, such as its spectrum, peak intensity, time dependence, and total energy, are calculated.

[en] For spectral features description of plasma containing lithium-like (or hydrogen-like) ions a model was developed which is based on steady state kinetic equations for density matrix. A solution of such equations is obtained from numerical code TRINITY. This code permits calculations of excited level populations as well as spectral gain and line profiles for emission and absorption for transitions between levels with principal quantum numbers up to 5. The model takes into consideration the influence of plasma microfields which leads to mixing of sublevels and Stark broadening of line shapes including non-linear interference effects due to coherent excitation of sublevels

[en] Simulations of gain in recombining laser-produced plasma of Li-like ions of aluminum were performed using the 2-D code GIDRA-2. Symmetrical 4-beam scheme of fiber irradiation was modeled in accordance with experimental arrangement described in Ref. (1). These simulations show good agreement with earlier 1-D simulations for optically thin plasma. Maximal angle-averaged value of gain on 3d_5/2-4f_7/2 transition in Li-like aluminum calculated using Sobolev approximation for photon escape probability and the Doppler line profile was 0.95 cm^-1. These 2-D simulations also show more realistic laser energy absorption (25-30% in 2-D simulations compared to nearly 90% in 1-D simulations and 6% in experiments)

[en] The characteristics of possible chain explosive hydrogen burning reactions in an oxidizing medium are calculated on the potential energy surface. Specifically, reactions H₂ + O₂ → H₂O + O, H₂ + O₂ → HO₂ + H, and H₂ + O₂ → OH + OH are considered. Special attention is devoted to the production of a pair of fast highly reactive OH radicals. Because of the high activation threshold, this reaction is often excluded from the known kinetic scheme of hydrogen burning. However, a spread in estimates of kinetic characteristics and a disagreement between theoretical predictions with experimental results suggest that the kinetic scheme should be refined.

[en] Experiments were conducted to study a continuously working e-beam ionized dusty plasma at atmospheric pressure in argon and nitrogen. The formation of highly ordered dusty structures of glassy carbon spherical particles in argon was observed at a gas ionization rate of about 10¹⁴ cm^-3 s^-1. A numerical simulation of charging dust particles and non-self-sustained discharge structures was performed. The dust particle trap formation in the cathode sheath of a non-self-sustained discharge was identified theoretically

[en] This article is a critical review of publications devoted to studying the electrostatic interaction of two charged macroparticles in an equilibrium plasma. It is shown from an analysis of the force of interaction based on the Maxwell stress tensor that two macroparticles with identical charges in the Poisson–Boltzmann model always repel each other both in isothermal and nonisothermal plasmas. At distances between macroparticles for which the Boltzmann exponents can be linearized, the interaction between macroparticles is completely described by the Debye–Hückel model. The correction to free energy due to the electrostatic interaction in the system of two macroparticles is determined by integrating the correction to the internal energy and by direct calculation of the correction for entropy. It is shown that the free energy coincides with the Yukawa potential. The coincidence of the interaction energy obtained by integrating the force of interaction with the free energy leads to the conclusion about the potential nature of the force of interaction between two macroparticles in an equilibrium plasma. The effect of the outer boundary on the electrostatic interaction force is analyzed; it is shown that the type of interaction depends on the choice of the boundary conditions at the outer boundary. It is also shown that the accumulation of space charge near the outer boundary can lead to the attraction of similarly charged particles at distances comparable with the radius of the outer boundary

[en] An analytical expression for the redistribution function of resonance radiation in plasma is found, using an atom+field density matrix approach to describe interaction with the quantized radiation fields. The relaxation of the atoms with degenerate structure of the levels is modeled using relaxation constants. The polarization of the emitted and absorbed photons are thus taken into account easily, with the scattering event being described by the redistribution tensor

[en] The conversion efficiency of a heat flux into hard X-ray radiation is analyzed for a heat-to-radiation flux converter linked to the edge of low atomic number hot Z-pinch using a time-dependent two-temperature one-dimensional non-LTE-radiation-hydrodynamic numerical model. The model gives a parameter regime with about the same hard x-ray yield as a radially imploding plasma, but with an order of magnitude lower input energy