Spatial structure and parameters of the predischarge channels in dielectric liquids of various molecular structure

Time-resolved pictures of the discharges with simultaneous recording of predischarge current have been obtained in transformer oils and in per-fluorocarbon liquid under a positive impulse in a sharply non-uniform field. The inception of the stepwise - flash propagation process (SFP) of discharge was observed in both liquids. It is shown that the inception voltage of the SFP can be important parameter closely related to the breakdown voltage of the liquids.