三电极气体火花开关触发过程中的等离子体行为特性

Plasma Evolution in Trigger Process of Three-electrode Gas Spark Gaps

三电极气体火花开关放电导通时的触发过程对其性能有着重要影响,而实验中发现某些三电极气体火花开关在触发过程中可能存在触发极与阴极和阳极几乎同时导通的问题,为了解释这种现象,利用PIC-MCC（网格粒子法耦合蒙特卡罗碰撞）程序建立了对应的三电极气体火花开关触发过程仿真模型,获得了电子、离子在触发过程中的时空分布演化特性及电场分布特性,阐明了触发过程中触发极与阴极、触发极与阳极形成等离子体通道的物理机理,分析了电场分布和绝缘体表面电荷累积效应等对触发过程中等离子体通道形成的影响,揭示了绝缘体表面二次电子发射等是导致触发极与阴极、触发极与阳极几乎同时形成等离子体通道的关键因素。这些都为进一步深入研究三电极气体火花开关,提高其工作性能奠定了坚实的基础。

Trigger process for initial breakdown between trigger and cathode is important to the performance of three-electrode gas spark gaps. However, it was experimentally observed that breakdown nearly coinstantaneously formed between trigger-cathode and trigger-anode in some three-electrode gas spark gaps by the help of high speed camera. Hence, we established a simulation model for the trigger process in the experimental three-electrode gas spark gap by PIC-MCC code, Moreover, we obtained the temporal and spatial density distribution evolution of electrons and ions,explained the mechanism of forming plasma channel between trigger and cathode（or anode）, and analyzed the influences of electric field distribution and charge accumulation on trigger process. It is revealed that the secondary electron emission on the insulator is the main factor to the breakdown coinstantaneously formed between trigger-cathode and trigger-anode in three-electrode gas spark gaps. It will be helpful to further optimize the performances of three-electrode gas spark gaps.