Effect of additives on the direct breakdown voltage of silicone oil in highly nonuniform fields

This paper reports some of the results obtained from extensive tests on the variation of the breakdown voltage with gap length for polydimethylsiloxane (viscosity S0 cST) under highly nonuniform fields. Tests were carried out on degassed silicone oil, oxygen-saturated oil & on degassed & oxygen-saturated oil containing varying concentrations (0.05 to 1 molar) of methylnaphthalene (MN) & dimethylaniline (DMA) as additives were chosen because results have been published [1] on the effect which they have on the propagation velocities of positive & negative streamers, & it was desired to investigate if there is any correlation between streamer velocity and breakdown voltage.