ИСТИНА

The paper studies streamer-to-filament transition in the single shot surface nanosecond dielec-tric barrier discharge (nSDBD) at high pressures, P = 1 - 10 bar. The high voltage nSDBD at atmospheric pressure develops as a set of parallel plasma channels - streamers, with electron density about Ne = 10(15) cm-3 and typical streamer channel diameter around 100 mkm. With pressure or voltage increase, a streamer-to-filament transition is observed, when, during 1 - 2 nanoseconds, a system of bright thin channels (filaments) is formed instead of the set of the streamers. The electron density rises up to Ne = 10(18)-10(19) cm-3, and according to our estimates, the diameter of the filament does not exceed a few tens of microns. The present paper is devot-ed to systematic experimental study of the streamer–to–filament transition in N2 : O2 mixtures, the percentage of oxygen being between 0% and 20%. The electron temperature in the dis-charge and near afterglow is measured in molecular nitrogen at gas pressure P = 6 bar from the Boltzmann the optical emission spectroscopy.