Factors affecting homogeneity of a nanosecond impulse barrier discharge in air at atmospheric pressure and its physical nature

Factors determining the existence of a homogeneous impulse dielectric barrier discharges in air at atmospheric pressure are analyzed based on the results of the performed experimental investigations. In particular, the impact of the rate of voltage rise on the front of the applied impulses and the distance between the electrodes on discharge homogeneity is examined. In the experiments, the discharge was initiated in gaps (0.25 – 4) mm between flat electrodes, where one of them was covered with a glass barrier, by applying voltage impulses with the steepness (0.25 – 2.2) kV/ns. The homogeneity of the discharges is determined from the photographs obtained during a single voltage pulse. It is found that charges deposited on the barrier surface by discharges occurring during sequentially applied voltage impulses create a stochastic pattern provoking the appearance of radiation zones with different intensity. It is concluded that electrons concentration (105 – 108) cm-3 needed for generation of a homogeneous discharge is provided by pre-ionization of gas by successive discharge impulses.impulses.