Effects of additives on prebreakdown phenomena in n-hexane

Abstract

Breakdown phenomena in n-hexane are observed in detail for positive and negative polarities by using a high-speed schlieren technique and an LED (light emitting diode) current measuring system, where an impulse voltage-(1.1/225 /spl mu/s) is applied to a point-to-plane electrode gap. The effects of several additives on the streamer propagation are investigated. In particular, the effects of electron-trapping additives on the negative streamer propagation and of low-ionization-potential additives on the positive streamer propagation are examined. Correlation between the shape and the propagation velocity of streamers is also discussed. The propagation of positive streamers found to accelerate in the presence of additives which have a low ionization potential, whereas the negative streamer velocities increase in the presence of additives which have a large electron-trapping cross-section.