S. I. Popel

Shock waves in charge-varying dusty plasmas and the effect of electromagnetic radiation

Nonlinear electrostatic wave structures in dusty plasmas in the presence of electromagnetic radiation are investigated. The dust charge variation is assumed to be caused by microscopic electron and ion currents at the grains as well as photoelectric current of electrons. Calculations of electromagnetic radiation effects are performed for the case of solar radiation spectrum in the vicinity of the earth. The exact solutions of the nonlinear equations, describing variable-charge dust grains, Boltzmann electrons, and inertial ions, are obtained in the form of steady-state shocks. The conditions for their existence are found. The dissipation in such shock waves originates from the process of dust charging. The possibility of observation of shock waves related to the dust charging process in the presence of electromagnetic radiation in active rocket experiments which involve the release of some gaseous substance in near-earth space is discussed.

Dusty Plasma at the Surface of the Moon

A theoretical model that provides a self-consistent description of the concentrations of photoelectrons and dust particles located over the illuminated part of the lunar surface is presented. The model takes account of the observation point location and the effects of production of photoelectrons at the surfaces of the Moon and dust particles, the dynamics of dust particles in the electric and gravitational fields, and the charging of dust particles through their interaction with the solar radiation photons, the solar wind electrons and ions, photoelectrons, etc. An expression that describes the distribution of photoelectrons over the illuminated part of the lunar surface is obtained. The size and elevation distributions of the charged dust particles located over the illuminated part of the lunar surface are calculated for different angles between the local normal and the direction to the Sun. It is shown that no substantial restrictions are imposed on the choice of the landing site for future lunar spacecraft missions aimed at studying the near-surface dust on the Moon.

Dissipative processes during the propagation of nonlinear dust ion-acoustic perturbations

A comparative analysis of various dissipative processes occurring on ion-acoustic time scales during the excitation and propagation of nonlinear dust ion-acoustic perturbations in a complex (dusty) plasma is performed in terms of a purely kinetic approach and a hydrodynamic approach. It is found that the most important dissipative processes are the charging of dust grains, the absorption of ions by grains, the transfer of the ion momentum to the grains, and Landau damping. The damping rate of dust ion-acoustic waves is derived based on a purely kinetic approach to describing complex plasmas; this makes it possible to eliminate all of the earlier contradictions in the description of Landau damping in a complex plasma. The relative roles played by dissipative processes in different laboratory experiments with dusty plasmas are compared.

Dusty plasma system in the surface layer of the illuminated part of the moon

The dusty plasma system in the surface layer of the illuminated part of the Moon has been considered. The maximum height of the dust rise has been determined. It has been shown that a dead zone, where dust particles cannot rise over the surface of the Moon, is absent near a lunar latitude of 80°. The size and height distributions of dust have been determined.

Evolution of weakly dissipative hybrid dust ion-acoustic solitons in complex plasmas

Possibility for hybrid ion-acoustic solitons to exist in complex (dusty) plasmas is investigated. Rarefactive solitonlike perturbations are damped and slowed down, mainly due to the plasma absorption and ion scattering on microparticles. Nevertheless, the amplitude of the evolving perturbation at any moment is given by the amplitude of the “conservative” soliton for the corresponding Mach number (so far as the conservative soliton exists). That property allows us to interpret the evolving rarefactive perturbation as a “weakly dissipative” hybrid dust ion-acoustic soliton. The weakly dissipative hybrid dust ion-acoustic solitons can be studied experimentally in laboratory complex plasmas.

Phenomena associated with complex (dusty) plasmas in the ionosphere during high-speed meteor showers

Formation of dusty plasmas in the Earth’s ionosphere at 80–120 km altitudes during high-speed meteor showers and its detectable manifestations are discussed. Emphasis is given to ground-based observations such as detection of low-frequency (<50 Hz) ionospheric radio noise, ground-based observations of infrasonic waves, and amplification of the intensity of green radiation at 557.7 nm from a layer at the 110–120 km altitude in the lower ionosphere. The physical processes responsible for these manifestations are considered.

Evolution of perturbation in charge-varying dusty plasmas

The nonstationary problem of the evolution of perturbation and its transformation into nonlinear wave structure in dusty plasmas is considered. For this purpose two one-dimensional models based on a set of fluid equations, Poisson’s equation, and a charging equation for dust are developed. The first (simplified) model corresponds to the case [Popel et al., Phys. Plasmas 3, 4313 (1996)] when exact steady-state shock wave solutions can exist. This simplified model includes variable-charged dust grains, Boltzmann electrons, and inertial ions. The second (ionization source) model takes into account the variation of the ion density and the ion momentum dissipation due to dust particle charging as well as the source of plasma particles due to ionization process. The computational method for solving the set of equations which describe the evolution in time of a nonlinear structure in a charge-varying dusty plasma is developed. The case of the evolution of an intensive initial nonmoving region with a constant enh...

On the distributions of photoelectrons over the illuminated part of the moon

The existing view of the photoemission properties of lunar regolith does not provide the unambiguous treatment of the parameters and distributions of photoelectrons over the illuminated part of the Moon. This is indicated by the present calculations of the density, temperature, and distribution function of photoelectrons. It has been demonstrated that the quantum yield of lunar regolith is the main parameter determining the generation of photoelectrons near the surface of the Moon. At present, this parameter is determined with significant uncertainty. The measurement of the quantum yield of regolith directly on the surface of the Moon has been proposed as a variant of the solution of the indicated problem. Such measurements can be performed in the framework of future lunar missions.

Dissipative processes and dust ion-acoustic shocks in a Q machine device

A comparative analysis of the most important dissipative processes occurring during the excitation and propagation of dust ion-acoustic shocks in a Q machine device, among which are the charging of dust grains, the absorption of ions by grains, the transfer of the ion momentum to the grains, and Landau damping, is performed. The relative roles played by dissipative processes in different types of laboratory experiments with complex plasmas are estimated.

Dust Acoustic Solitons in the Dusty Plasma of the Earth's Ionosphere

Stratified structures that are observed at heights of 80–95 km in the lower part of the Earth’s ionosphere are known as noctilucent clouds and polar mesosphere summer echoes. These structures are thought to be associated with the presence of vast amounts of charged dust or aerosols. The layers in the lower ionosphere where there are substantial amounts of dust are called the dusty ionosphere. The dust grains can carry a positive or a negative charge, depending on their constituent materials. As a rule, the grains are ice crystals, which may contain metallic inclusions. A grain with a sufficiently large metallic content can acquire a positive charge. Crystals of pure ice are charged negatively. The distribution of the dust grains over their charges has a profound impact on the ionizational and other properties of dust structures in the dusty ionosphere. In the present paper, a study is made of the effect of the sign of the dust charge on the properties of dust acoustic solitons propagating in the dusty ionosphere. It is shown that, when the dust charge is positive, dust acoustic solitons correspond to a hill in the electron density and a well in the ion density. When the dust is charged negatively, the situation is opposite. These differences in the properties of dust acoustic solitons can be used to diagnose the plasmas of noctilucent clouds and polar mesosphere summer echoes.