金属微粒影响三电极气体火花开关击穿过程的仿真研究  

Simulation of effect of metal particles on breakdown process of three-electrode gas spark switches

作　　者：周鑫淼 张博雅 陈立[1] 李兴文[1] Zhou Xin-Miao;Zhang Bo-Ya;Chen Li;Li Xing-Wen(State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学,电工材料电气绝缘全国重点实验室,西安710049

出　　处：《物理学报》2024年第1期248-257,共10页Acta Physica Sinica

摘　　要：气体火花开关在脉冲功率技术中得到了大量应用,但由于脉冲功率技术大电流高电压的特点,气体火花开关在使用过程中很容易对电极表面造成烧蚀,烧蚀产生的金属微粒会显著影响开关的稳定性和可靠性.本文首先针对大气压氮气环境下的三电极气体火花开关放电过程进行建模,对触发极边缘高场强区域的电离系数进行修正,使用场致电子发射电流模拟初始电子产生的过程,深入探究开关导通的物理机理,详细叙述开关击穿过程各阶段的放电形态.接着研究了金属微粒对于击穿过程的影响,研究表明金属微粒的存在增强了触发极附近的电场,加速了初始电子云的产生,同时金属微粒与触发极之间会率先击穿,并成为后续流注发展的源头.除此之外,金属微粒对于流注的传播具有阻碍作用,使放电通道产生分支.最后本文讨论了不同形状以及尺寸的金属微粒对于放电过程的影响,这些都为进一步研究三电极气体火花开关放电过程以及金属微粒诱发开关击穿的物理机理提供了理论支撑.Compared with two-electrode gas spark switch,three-electrode gas spark switch has the advantages of lower operating voltage,higher reliability and less discharge jitter,so it has been widely used in pulse power systems.However,due to the characteristics of pulse power technology,the gas spark switch is easy to cause ablation on the electrode surface during use,and the metal particles generated by ablation will significantly affect the stability and reliability of the switch.In this work the discharge process of the three-electrode gas spark switch under atmospheric pressure nitrogen environment is simulated first.In this model,the ionization coefficient near the trigger electrode is modified to compensate for the shortcomings of the local field approximation,and the relevant mathematical derivation process is given.The formation of the initial electrons is described by the field electron emission phenomenon,and the development process of electron collapse into the streamer is obtained.The physical mechanism of switch on is investigated,and the development process of each stage of switch discharge is described in detail.Then,the discharge process of the switch is studied when there are metal particles near the trigger.The study shows that the presence of metal particles enhances the electric field near the trigger and accelerates the formation of the initial electron cloud.In addition,in the presence of metal particles,the metal particles and the trigger will first break down,forming a high-density plasma channel after the breakdown,and becoming the source of the subsequent flow development.At the same time,because the metal particles on the channel have an obstructing effect on the streamer development,the streamer generates a discharge branch after contacting metal particles.In the end,the influences of metal particles of different shapes and sizes on the discharge process are discussed.The results show that metal particles with sharp shapes have stronger electric field distortion,when the electric field intensi

关 键 词：流注放电 气体火花开关 金属微粒 场致发射 

分 类 号：TN78[电子电信—电路与系统] O461.2[理学—电子物理学]