Vol 44, No 8 (2018)

A theoretical investigation on the effect of electrostatic interaction on dust acoustic wave (DAW) has been carried out in weakly nonlinear limit in strongly coupled regime with fluctuating dust charge. The generalized hydrodynamic set of equations is employed in the hydrodynamic limit. The dust−dust electrostatic interaction couples with dust charge fluctuation, as well as the viscosity of the medium, and provides the dissipative effect, which leads to the formation of shock wave in such a system. The novel feature of the present work is that, in the presence of charge fluctuation, the effective electrostatic temperature starts affecting the behavior and also enhancing the formation of monotonic shock wave. In this investigation, the dissipative effect arising due to charge fluctuation is dominant in comparison to the viscosity of the medium in the presence of electrostatic temperature.

It is shown that plasma parameters, such as the electron density, electron temperature, and plasma potential, in multidipole discharge plasma can be controlled by a negatively biased movable metal plate. Here, plasma is produced in the target region by a flux of energetic electrons coming from the source region of a double plasma device. Further, the thickness of the ion sheath formed in front of the biased metal plate varies depending on its axial position inside the cage.

Results are presented from experimental studies of a pulsating discharge produced by a dc power source in subsonic and supersonic cold (T = 150–300 K) air flows at static air pressures in the flow of 40–760 Torr. Two modes of pulsating discharge were implemented experimentally: without and with (from one to five) intermediate breakdowns. The discharge pulsation frequency, the maximum attainable voltage across the discharge gap, the length of the plasma channel, and the electric field in the discharge plasma were studied as functions of the air flow velocity and discharge current.

The dispersion law and collisionless damping rate of quasi-potential waves in the plasma formed upon tunnel ionization of gas atoms in the field of a short pulse of circularly or linearly polarized radiation are found. It is shown how the frequency and damping rate of quasi-potential waves depend on the wave propagation direction relative to the symmetry axis of the photoelectron distribution. It is established that, in plasma with a toroidal photoelectron velocity distribution, weakly damped waves with a linear dispersion law and frequency above the electron plasma frequency can propagate in a wide range of angles. In the case of a bi-Maxwellian photoelectron distribution, the frequency of weakly damped waves is comparable with the electron plasma frequency and the anisotropy of electron motion manifests itself in relatively small corrections to the dispersion law.

The recombination kinetics of chlorine atoms on the wall of a plasmachemical reactor and on silicon samples in the positive column of a glow discharge in Cl₂ has been studied experimentally. The rate constants and probabilities of the heterogeneous recombination of chlorine atoms on the plasma limiting surfaces, as well as of the chemical interaction of chlorine atoms with silicon, are calculated. The temperature and time dependences of the probabilities of the chemical interaction of chlorine atoms with silicon are analyzed, and optimal conditions for conducting pulse relaxation experiments are determined.

The formation of dusty plasma in the near-surface layer above the illuminated part of the Deimos, the satellite of Mars, due to photoelectric and electrostatic processes is analyzed. Using a physicomathematical model self-consistently describing the densities of photoelectrons and dust grains above the illuminated part of Deimos, the distribution function of photoelectrons near its surface is calculated and the altitude dependences of the electric field, as well as of the number density, charge, and size of dust grains, are determined. It is noted that, due to the lower gravity, substantially larger grains are lifted above the surface of Deimos compared to those lifted above the Moon’s surface. In this case, adhesion, which is believed to significantly hamper the detachment of dust grains from the lunar surface, plays a substantially smaller role on Deimos.