Nanosecond repetitively pulsed discharges in air at atmospheric pressure - The glow regime

In atmospheric-pressure air preheated to 1000 K, nanosecond repetitively pulsed (NRP) discharges are shown to generate three plasma discharge regimes. In addition to the well-known corona and spark regimes, there exists a glow-like regime that develops through an initial cathode-directed streamer, followed by a return wave of potential redistribution. The applied electric field is then switched off before the formation of the cathode fall, resulting in an 'imminent' glow discharge. Previously, this regime had been observed only at 2000 K in air at atmospheric pressure. Measurements of the plasma dynamics, current-voltage characteristics, gas temperature and plasma chemistry of the excited species N₂(B), N₂(C), , NO(A) and O(3p ⁵P) in the pulsed glow regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that this glow regime generates an estimated electron number density of 10¹³ cm^-3, while consuming only 1-10 νJ per pulse and heating the gas by less than 200 K.