Variation in the nature of prebreakdown streamers in liquid dielectrics

Optical techniques have previously been established and used to record the events that lead to breakdown in liquid insulants. Schlieren, shadowgraph, and scattered light arrangements have been employed to render visible the refractive index perturbations induced by the prebreakdown disturbances [1-4]. Although some uniform field studies have been made [4], most work has been accomplished using highly divergent electrode configurations in order that polarity effects may be separated.