Electron kinetics in standing and moving striations in argon gas

TL;DR

This study investigates electron behavior in standing and moving striations within argon plasma discharges, revealing non-local transport and non-equilibrium energy distributions, with differing dynamics between DC and RF discharges.

Contribution

It introduces a hybrid modeling approach to analyze electron kinetics in non-thermal plasma striations, highlighting differences in electron response between DC and RF discharges.

Findings

Electron transport is non-local in space.

Electron energy distribution is non-equilibrium.

Electron dynamics differ significantly between DC and RF discharges.

Abstract

The electron kinetics in moving and standing striations in direct current and radio-frequency discharges is studied. The discharge current is such that the thermalizing electron-electron collisions are negligible and the hydrodynamic description of electron component of plasma is not valid. Therefore, the one-dimensional hybrid model is used which models the electron component by particle method, while the ions are described using the drift-diffusion approximation. It is obtained that the electron transport is non-local in space. The electron energy distribution in both discharges is of non-equilibrium nature which is responsible for the non-linearity of the ionization frequency. However, their dynamics in both discharges differs significantly. Namely, in the direct current discharge the distribution function is strongly modulated by the striations passage, while in the radio-frequency discharge the electron energy relaxation time is such that the electron distribution function does not react on the oscillating electric field but is defined by the effective electric field.