Nanosecond surface dielectric barrier discharge in high pressure air at different polarities of applied pulses. Transition to filamentary regime.

Nanosecond pulsed discharge transformation with pressure is discussed. Experimental measurements present, at elevated pressures, transition from "uasi-uniform" streamer discharge to flamentary structure. Conditions of the appearance of the transition regime as a function of voltage and gas pressure are presented. It is shown that there is no increase of the deposited energy during the transition, and that the flamentary form of the discharge remains low temperature and low current discharge. Theoretical estimates and numerical modeling show that ionization overheating instability on the boundary of the cathode layer can be suggested as a mechanism of flamentation.