Generation of diffuse air plasmas at atmospheric pressure using nanosecond repetitively pulsed discharges

A diffuse non-thermal plasma regime in air at atmospheric pressure from 300-1000 K has been generated using the nanosecond repetitively pulsed method. This diffuse plasma develops through an initial cathode-directed streamer, followed by a return wave of potential redistribution. Furthermore, at a given gas temperature, there is a minimum gap distance required for the existence of the diffuse regime. The sequence of events observed in the formation of the diffuse plasma lead us to conclude that it is an "imminent" glow discharge. The applied electric field is maintained long enough (~10 ns) to initiate a streamer that interacts with the cathode to produce a return wave. However, the field is switched off before the development of significant ion- electron emission, which requires tens of nanoseconds. This limits the formation of the cathode fall, thus avoiding the imminent creation of a glow discharge.