Experimental and theoretical study of the transition between diffuse and contracted forms of the glow discharge in argon

Abstract

The constriction of the positive column of a glow discharge in argon was studied both experimentally and theoretically. In experiments the direct current discharge was maintained in a cylindrical glass tube of 3 cm internal diameter and 75 cm length. The voltage–current U(I) characteristics of the discharge were measured at a gas pressure P from 1 to 120 Torr in a wide range of discharge currents. At P > 20 Torr the measured U(I) characteristics display the classical hysteresis effect: the transition from the diffuse to the contracted discharge form (with increasing current) occurs at a current higher than that for reverse transition (with decreasing current). It was also found that in some cases the so-called partially contracted form of the discharge is realized, when the diffuse and contracted forms coexist in the discharge tube.To calculate the plasma parameters under experimental conditions a 1D axial-symmetric discharge model for pure argon was developed. The details of the model are described and the results of simulations are presented. In particular, the electric field strength E in the positive column was calculated as a function of the discharge current. Theoretical E(I) characteristics are compared with those derived from the experiment. For the first time, the detailed kinetic model without the usage of fit parameters predicts the hysteresis effect in pure Ar with parameters of diffuse and constricted forms of the discharge in good agreement with the experiment.

Striated microdischarges in an asymmetric barrier discharge in argon at atmospheric pressure

“…8(b)]. This hysteresis behavior is well known from low-and medium-pressure glow discharges [6] and for the discharge constriction (with striated structure) [17] as well. It is a clear indication of nonlinear plasma processes [24,47,48].…”

“…When averaging λ e over the energy space using conforms to the mean energy in the transition region from glow to constricted mode obtained in [17,49].…”

“…Frequently, the striated structure within the plasma channel at low pressure appears as a result of a relaxation process induced by a local disturbance, which can be caused, for example, by a probe, a short laser pulse, or a discharge constriction [14][15][16][17]. However, these instabilities are not yet fully understood for atmospheric-pressure plasmas, which have been the subject of extensive research in the last decade [18].…”

On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

“…Though the term APGD is usually attributed to the glow-like discharge with a diffuse positive column, the glow discharge at elevated pressure can also exist with the positive column contracted to a filament. The nature of such contraction is related to the Maxwellization of the electron energy distribution function [20,28] or to a thermal instability [20].…”

Influence of driving frequency on discharge modes in a dielectric-barrier discharge with multiple current pulses

“…All the reaction rates are referred to those used in Refs. [25][26][27]. The densities of all the particles are described by the continuity equation: @n k ðy; tÞ @t þ @j k ðy; tÞ @y ¼ S k ðy; tÞ;…”