Prebreakdown phenomena in sphere-sphere electrode configurations in dielectric liquids

Negative streamer growth is observed in a highly refined mineral oil for sphere-sphere electrode configurations. The shape of the streamers is somewhat different from that found in point-plane geometries. The addition of electron trapping additives accelerates the negative streamer velocity as was found to be the case in point-plane geometry. Breakdown occurs before the negative streamer crosses the gap and appears to originate at the anode. Very fast positive streamers are, in fact, observed.