This paper presents radial distribution functions of dust particles obtained experimentally in dc and rf discharges. Pressure and interaction energy of dusty particles were calculated on the basis of these functions. The Langevin dynamics computer simulation for each experiment was performed. The comparisons with computer simulations are made.

The paper reports on the first experiments with plasma-dust formations in dc gas discharge plasma for a He-Ar mixture. It is shown that the choice of light and heavy gases for the mixture suppresses ion heating in electric field under the conventional conditions of experiments and results in a supersonic jet with high Mach numbers. Distribution functions for drifting ions in the gas mixture are calculated for various mixture concentrations, electric field strengths, and gas pressures.

Experimental investigations of dusty plasma parameters of a dc glow discharge were performed in a vertically oriented discharge tube. Under certain conditions, dust-free regions (voids) were formed in the center of the dust particle clouds that levitated in the strong electric field of a stratified positive column. A model for radial distribution of dusty plasma parameters of a dc glow discharge in inert gases was developed. The behavior of void formation was investigated for different discharge conditions (type of gas, discharge pressure, and discharge current) and dust particle parameters (particle radii and particle total number). It was shown that it is the ion drag force radial component that leads to the formation of voids. Both experimental and calculated results show that the higher the discharge current the wider dust-free region (void). The calculations also show that more pronounced voids are formed for dust particles with larger radii and under lower gas pressures.

We present the experimental results on influence of an external magnetic field on the dust particles which were suspended in the strata of a glow discharge, where the magnetic field was created using a Helmholtz coil. Observations were made in the strata that located between the coils, under the coil, and above the coil. We observed an interesting behavior of dust particles, which was not previously reported. It was revealed that the dust structure rotates clockwise above the coil and counterclockwise under the coil, while the dust structure located between the coils does not rotate. Experiments were performed with both mono- and poly-disperse dust particles at B łe 28 mT. The radial distribution of the angular velocity of dust particles, at the induction of the magnetic field 8, 13, and 19 mT, in different regions was measured. For explanation of the experimental results, we developed a simple theoretical model which shows that the direction of the rotation is determined by the radial component of the magnetic field induction.

Dependence of diffusion coefficient of dusty particles in dusty plasma was experimentally obtained. A proportional increase of diffusion of the dust particles with the increase of the discharge power was experimentally found. The pair correlation functions of dusty particles were also obtained from the experiments and the change of dust cloud structure with the increase of the discharge power was observed. The influence of the dust particles on the spectrum of plasma glow was investigated using spatial spectrometer. It was shown that upon introduction of dust particles into the plasma bulk the overall intensity of the plasma glow decreases.