Influence of Gap Spacing between Dielectric Barriers in Atmospheric Pressure Discharges

The breakdown activity in helium atmospheric pressure dielectric barrier discharge (DBD) plasma is strongly modified by introducing small impurities (nitrogen (N-2) and air in ppm), although its precise implications for the behavior of discharge plasma is not evident under several constraints. In this simulation study, we investigate the influence of gap spacing between the dielectric barriers to explore the dynamic modification in the structure of discharge plasma in distinct phases of the discharge current pulse using a two-dimensional fluid model in He-air gas mixture. Specifically, the impact of nitrogen and air impurities is contrasted by exploring the spatial distributions of electrons in the breakdown phase under similar operating conditions. The filamentary mode of DBD plasma in He-N-2 is transformed into uniform glow discharge in He-air gas mixture by the dominant effect of Penning ionization. Finally, the outcomes of two-dimensional fluid model are validated by comparing with three-dimensional fluid model to provide the reliability of numerical simulations. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim