Characteristics of propagating electrostatic discharges on dielectric films

Abstract

Spark discharges that occur as a spherical, earthed electrode approaches the charged surface of an insulating sheet lying on an earthed base change in character as the initial surface charge density increases. Above a certain charge level the discharge no longer remains localised in the region directly opposite the electrode, but propagates vigorously over large areas. The threshold charge density for such propagation was found to vary with the film thickness. The criterion governing the threshold behaviour is discussed from a mechanistic viewpoint.