大气压下不同气体的流注放电特性

Properties of Streamer Discharges in Different Gases at Atmospheric Pressure

大气压下气体放电通常表现为丝状放电形式。流注或先导放电是其气体击穿的起始阶段,相对于低气压下暗放电或辉光放电具有更复杂的演化特性。为了研究不同气体的流注传播特性,采用流体模型对1 cm平板电极中大气压下氮气、氧气,以及氮气混合20%、1%和0.01%氧气的双向流注传播过程进行了仿真计算。光电离作为源项加在流体模型中,在数值仿真时采用解多组Helmholtz方程代替Zheleznyak积分计算。仿真结果表明:氧气含量较低时,流注会出现分叉现象;氧气中流注发展速度较快;氧气中正流注通道半径较大。

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 eva- luating the integral proposed by Zhelcznyak 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.