Properties of streamer discharges in different gases at atmospheric pressure

Usually discharges at atmospheric pressure take the form of filamentary discharges. Its first stage is the process of streamer or leader breakdown, which proceeds in a more complex way than dark or glow discharges at low pressure. In order to investigate the characteristics of streamer propagation in different gases, the propagation of a double-headed streamer between two parallel plate electrodes with 1 cm gap in pure nitrogen, pure oxygen, and nitrogen mixed with 20%, 1% and 0.01% oxygen in volume at atmospheric pressure is modeled by the fluid approach. In the model, photoionization is taken into account through a source term which is derived by solving multi-group Helmholtz equations instead of evaluating the integral proposed by Zheleznyak et al. The results show that branching occurs if the oxygen content is low, and in oxygen the propagation velocity is slightly faster and the radius of positive streamer channels is larger. ©, 2015, Science Press. All right reserved.