The transition from a filamentary dielectric barrier discharge to a diffuse barrier discharge in air at atmospheric pressure

A transparent plasma discharge reactor using air was used to investigate the transition from a filamentary dielectric barrier discharge (FDBD) operation regime into the diffuse barrier discharge regime. Recent results of other researchers indicate that the stability of diffuse barrier discharges in nitrogen may be attributed to the lack of a fully formed cathode fall layer when the discharge operates in a regime between the Townsend discharge and a normal glow discharge. We have demonstrated that a diffuse barrier discharge in air exhibits an increased accumulation of electric charge on the electrode's dielectric plates as compared with the FDBD. This may provide a means of stabilizing the discharge in a Townsend-to-glow discharge transition. Unlike operation in nitrogen, a streamer mechanism is involved in the formation of a uniform air plasma, though in a different manner than is associated with the FDBD. Numerous diffuse streamer clusters were observed on pre-charged dielectric plates at the breakdown voltage. Our conclusion is that the macroscopically uniform atmospheric-pressure DBD in air is obtained by the numerous radially expanding streamers that are temporally overlapping.