Streamer propagation along insulating surfaces

Results concerning the propagation of streamers along insulating surfaces u nder uniform electric field are presented. The basic properties of streamer s, namely the electric field required for a stable propagation and the prop agation velocity, have been measured and compared with propagation in air a lone as a reference. The results have shown that in the experimental arrang ement used significant space charges due to streamer branching are absent, therefore the properties observed are considered as characteristic of a sin gle streamer. Streamers propagate stably with an intrinsic propagation fiel d and a characteristic velocity that depend on the nature of the insulating material. For electric fields higher than the minimum field required for a stable propagation, a streamer system propagates with a 'surface' and an ' air' component.