运动微粒导致间隙击穿的模拟研究

Gas Discharge Induced by Microparticles Moving between Two Parallel Electrodes

当在充满气体的两电极平板间隙中,运动的带电微米级微粒由于外力作用运动到电极表面附近时,可能会引起微粒与电极间局部微放电,甚至在一定条件下可能会引发间隙气体击穿,这是一种非常特殊的击穿现象。因此,本文通过理论公式和静电场模拟,分析了不同大小的带电微粒距离阴极表面不同距离的电场畸变情况;接着基于二维轴对称网格粒子法耦合蒙特卡洛碰撞(PIC-MCC)算法,建立了带电微粒距离电极表面1μm处引发间隙气体击穿的仿真模型,并与不考虑微粒的仿真计算结果进行了对比,获得了电子、离子在不同情况下的时空分布演化过程,揭示了带电微粒接近导致阴极表面电场增强从而发射场致电子是引发间隙气体击穿的首要原因,并阐明了这些电子引发间隙击穿的物理机制。这为进一步深入理解运动微粒引发间隙击穿的物理机理奠定了基础。

The localized discharge,originating from the micrometer-sized charged particles moving between the parallel electrodes filled with 1.0 atm N2,was empirically approximated,mathematically modeled,theoretically analyzed,and numerically simulated in 2 D particle-in-cell Monte Carlo collision(PIC-MCC) code to understand the breakdown mechanism(s).The influence of the physics,including the field emission of primary/secondary electrons,field enhancement factor of cathode and gas ionization,on the discharge was investigated.The time evolution of electron/ion distributions was calculated.The simulated results show that the highly localized field emission of primary(seed) electrons,induced by the positively charged micro-particles approaching the cathode,has a major impact.To be specific,these "seed electrons" are responsible for field distortion,large field enhancement factor,gas ionization and secondary electron emission.Consequently,it is the seed electrons that possibly ignite the breakdown of the gap.