On the relation between the index of the interelectrode gap filling with spark channels and the current of a pulsed multichannel sliding discharge in Ne, Ar, and Xe

Abstract

Experimental results and model concepts concerning the relation between the index K of the interelectrode gap filling with spark channels and the peak current I _peak of a single-pulse submicrosecond multichannel complete sliding discharge on an alumina ceramic surface are discussed. The spatial structure of an incomplete discharge at the threshold for the surface spark breakdown of gas is considered. The experiments were performed with three gases, Ne, Ar, and Xe, at pressures of 30 and 100 kPa and opposite polarities of the discharge voltage, with two discharge chambers differing in the geometry of the discharge gap and the thickness of the ceramic plate. It is shown that, although the structure of the incomplete discharge at the threshold for spark breakdown varies from diffuse homogeneous to pronounced filamentary, the dependence $K\left( {\sqrt[6]{{I_{peak} }}} \right)$ for a complete discharge is close to linear and can be qualitatively explained by the earlier proposed semiempirical model of the time evolution of the structure of a multichannel discharge. In particular, the estimated steepness of the dependence $K\left( {\sqrt[6]{{I_{peak} }}} \right)$ agrees best with the experimental results when the local density of free electrons at the threshold for spark breakdown is 10¹⁶ cm⁻³ or higher.