Impedance, equivalent circuit and stability behaviour of medium-pressure discharges

Abstract

Ah equivalent circuir of a medium pressure column is derived at low current and stability behaviour is considered on this basis.Studies of the dynamic behaviour of discharges [1], [2] have shown that it is possible to derive quantitative information about the efficiency of va¡ elementary processes (direct ionization, stepwise ionization) in the discharge mechanism. This possibility is of particular importanee in instantes when single elementary processes (e.g. triple collisions) have but a small effect on the statie characteristics of a discharge, but a signifieant influence on the dynamic behaviour. From investigations of the dynamic behaviour it was found that tentative suggestions about the stability of the discharge [3], [4] could be made, although in order to get easily surveyable stability criteria ir was necessary t6 derive ah equivalent circuit of the discharge [5]. The positive low-pressure columns at weak currents have already been investigated in this direction. The object of this paper is first to derive an equivalent circuit of a positive medium-pressure column at low current and then to consider stability on this basis.