The comparison of the residual charge distribution of surface leader discharge under positive and negative impulse voltage application

Summary form only given. Flashover on insulator surface in the air at atmospheric pressure occurs as a sequence of several processes and leads to the formation of a plasma channel which bridges the electrode gap. The streamer-to-leader transition is a very critical stage of such a breakdown since the leader can propagate a long distance with a low increment of application voltage. The transition and the propagation process of a leader bas become the object of intensive experimental and theoretical studies.