On mechanisms involved in the propagation of subsonic positive streamers in cyclohexane

This paper presents a study of slow positive streamers in cyclohexane under impulse voltage. A high sensitivity differential technique is used to record the streamer charge, together with high speed visualization. At voltages below the breakdown voltage, streamers stop while the voltage is still applied. It is shown that the first event preceding stopping is the hydrodynamic collapse of streamer filaments close to the point. This collapse "propagates" from the point to the streamer head, and the streamer then totally disappears. As soon as the streamer collapse starts, the streamer current is stopped, no more electrical energy is supplied, and liquid vaporization ceases. However, the streamer head still propagates at a reduced velocity. These observations constitute a direct evidence of the influence of space charges and electric field (i.e. electrostatic pressure) on propagation processes.