Proposed theory for streamer-to-leader-transition in non-uniformfield air gaps subjected to positive switching-impulses

摘要

On the basis of a recent experimental investigation and animproved knowledge of physical processes in leader discharges, a theoryis presented to permit estimation of the field required forstreamer-to-leader transition at different humidities. It is clearlyshown that electron-impact ionization is the main parameter for leaderformation. Two predictions are made: the electric field necessary forleader formation is considerably lower than the field necessary for thefirst corona streamer formation (i.e., ~30 kV/cm). Secondly, this fielddecreases with increasing humidity