Nonlocal kinetics of the electrons in a low-pressure afterglow plasma

Abstract

Low-pressure pulsed plasmas are widely used in various technological applications. Understanding of the phenomena taking place in afterglow phase of the discharge makes possible the optimization of the operation conditions and improvement of the technical parameters. At low pressure the electron component of the plasma determines the main features of the discharge since its behavior dominates all other plasma properties. We study the electron kinetics in a low-pressure afterglow plasma of an inductively coupled discharge by means of a self-consistent model which uses the nonlocal kinetic approach. The main features of the model are given. Special attention is paid to determination of the steady state of the discharge from which the decay of the plasma begins. Emphasis is also put on the description of the collisional interaction between the electrons and gas. Results of theoretical investigations for argon at a pressure of 2-4 Pa are presented. Calculated temporal evolutions of the isotropic part of the electron velocity distribution function, electron density, mean electron energy, and wall potential are discussed in comparison with experimental data.

Afterglow of Argon Plasmas with H2, O2, N2, and CO2Admixtures Observed by Thomson Scattering

“…That is completely different in pure argon or helium where the depletion of the tail is followed by re‐distribution of the EEDF which subsequently leads to a much lower bulk‐ T e . (cf by modelling and Blois et al in experiments that the vibrational distribution function of N 2 (X) is also quite stable for precisely this time frame.…”

Experimental investigation of emission intensities in an inductively coupled afterglow neon plasma

“…Since the number density of 1s 3 atoms is always approximately a factor of five less than the number density of 1s 5 atoms, the second term can also be neglected. Therefore, we can get the emission intensity from (7), Since E 0,2p1 /T e is larger than four and the decay rate of T e is always faster than that of n e , the characteristic decay time of the line intensity at 585.2 nm is mainly determined by the second term on the right-hand side of (9). Then the first term can be neglected,…”

“…All these features of pulsed plasmas relate to the afterglow. Therefore, as one of the most important physical processes in the afterglow, the electron cooling mechanism or the relaxation mechanism of the electron energy distribution function (EEDF) has been investigated theoretically and experimentally in the past several years [4][5][6][7][8].…”

Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

“…[90][91][92][93][94] The effect of electron-electron interaction (Coulomb collisions) was found to play an important role in the evolution of the EEDF as the electron temperature decreases during the late afterglow. [92,95,96] Besides, collision processes of long lifetime metastable atoms and vibrationally excited molecules can lead to electron re-heating during the afterglow. [91,[97][98][99] Recently, experimental diagnostics and PIC/MCC simulations were combined to investigate the electron cooling, re-heating and plasma density decay processes during the afterglow of a pulsed CCP in argon.…”