微空心阴极放电的初始放电过程研究

Simulation of Initial Discharge of Micro-Hollow Cathode

运用权重粒子和电荷分配等方法将系综蒙特卡罗模型改进为自洽蒙特卡罗模型,方便地实现粒子系统与电场的自洽作用,既能完整地记录所有带电粒子在某一时刻的具体位置、运动方向和能量,又能获得自洽电场随时间的演变过程。使用该模型对矩形微空心阴极放电进行仿真,仿真结果表明高气压下的初始放电是阴阳极间电场和空间电荷电场共同作用的结果,由于阴阳极间电场的驱动作用,空间电荷构成的虚阳极首先在阳极表面形成,然后向对阴极内部扩展。因此高气压微空心阴极放电的初始放电过程也符合虚阳极移动理论,空心阴极鞘层结构的形成是虚阳极移动和扩展的结果。

The initial stage of micro-hollow cathode discharge was simulated with a self-consistent Monte Carlo model,formulated by modifying an ensemble Monte Carlo model by taking considerations of the weighted particles,distributions of electrons and ions,and Poison equation. Various variables,such as the spatial,energy and velocity distributions of electrons and ions,time evolution of electric fields were evaluated. The simulated results show that the superposed electric fields of the space-charges,anode and cathode have a major impact on the initial discharge at a high pressure. Driven by the potential difference between anode and cathode,the virtual anode,initially formed on the anode surface,propagates towards the hollow cathode,accompanied by formation of the cathode sheath of the hollow cathode. The virtual anode propagation model was found to describe well the initial discharge of micro-cathode at high pressure.