Characterization of millimeter magnitude atmospheric pressure glow discharge in pin-to-plane dielectric barrier discharge

Discharge mode in pin-to-plane dielectric barrier discharge at atmospheric pressure was investigated by means of the electrical measurement, the photo-electricity and the fast macro photography. The discharge was operated in atmospheric air. Streamer and glow discharge were generated in the positive half-period and negative half-period of discharge respectively with a 10 kHz AC power supply when the applied voltage reached a high value. The subject of this paper is the study of the characterization of the glow discharge. It was found that the glow discharge have the hierarchical structure, although the discharge gap is small (only 0.9 mm). The positive column is shortened as the distance of discharge gap decreases, but the dimensions of other discharge area do not change. The discharge current waveform illustrates that the positive half-period discharge current is very short, which is streamer current waveform, and the negative half-period one is longer, which is glow discharge current waveform. The photo-electricity signal waveform corresponds with discharge current waveform. Two main glow discharge generating reasons are proposed in this paper. One is a sufficient number of space charge produced in the very uneven electric field around needle electrode; the other is the effective secondary electron emission process on the exposed needle electrode.