Dust-void formation in a dc glow discharge

Abstract

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.

Non‐local electron kinetics around the cloud of dust particles

“…To highlight the self-consistent influence of a dust cloud on a DC discharge plasma, the previously developed [6,7] non-local model based on kinetic Boltzmann equation for EEDF, drift-diffusion equations for ions, and Poisson equation for self-consistent electric field was used. In the paper calculations were performed for two cases, that is, for fixed step-like radial distribution of dust particles density, and for self-consistent distribution of dust particles density calculated by the drift-diffusion equation.…”

“…To describe the electron component of the discharge plasma, a non-stationary non-local Boltzmann equation for isotropic part of EEDF f 0 (U, r, t) was used in the form [6,7] :…”

“…To obtain steady-state radial distributions of EEDF f 0 (U, r, t), ion density n i (r, t), dust particle density N d (r, t) and electric potential (r, t), a time-dependent procedure developed in Fedoseev et al [7] was used.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] It was understood that electron and ion losses on dust particle surface should be compensated for in ionizing collisions, and an averaged electric field should increase in the region containing dust particles. The influence of dust particles on gas discharge plasma is negligible only for low dust particles concentration and charge.…”

“…[6][7][8] For example, dust particle charging is provided by the electron and ion fluxes into the cloud from the surrounding plasma. [6][7][8] For example, dust particle charging is provided by the electron and ion fluxes into the cloud from the surrounding plasma.…”