基于高能逃逸电子机制的气体开关自击穿稳定性

Self-breakdown stability of gas switch based on high-energy runaway electron mechanism

为实现脉冲驱动源气体主开关的精确控制技术,研制了基于电晕稳定机理的气体触发开关,并对稳定电晕放电过程以及高能逃逸电子对击穿稳定性的影响进行分析,揭示了抑制高能逃逸电子产生有助于增加气体开关自击穿稳定性的机制。从气体介质和电场条件两个方面进行实验研究,对比该型气体开关的自击穿稳定性,实验结果表明:在气压0.06 MPa至0.56 MPa范围内,气体开关充15%SF_(6)/N_(2)混合气体,其自击穿离散度不超过6%,最低可达1.4%;当SF_(6)/N_(2)混合气体内的电负性气体占比小于30%时,气体开关的自击穿电压离散度保持在2%~4%范围内;在充电电压小于1800 V范围内,改变间隙内电场的时域变化速度,可降低自击穿电压的离散度,当电压上升速度为12.4 kV/μs时,自击穿电压为242 kV,离散度为0.2%;在0.3 MPa的15%SF_(6)/N_(2)混合气体内,降低触发极尖端的场不均匀系数,击穿稳定性未得到明显改善,但是在电场时域变化速度增加时,自击穿电压离散度依然可以保持在1%以下;利用沟槽型触发极代替楔形触发极,击穿电压离散度最低可达0.15%,且击穿电压稳定在248 kV附近。

To achieve precise control of the main triggered switch of the pulsed power source,a triggered gas switch based on the principle of corona stabilization was developed.The process of stabilized corona discharge and the influence of high-energy runaway electrons on the stability of breakdown were analyzed.This study also revealed the mechanism by which suppressing high-energy runaway electrons was beneficial in increasing the stability of gas switch self-breakdown.The experimental study was carried out from the perspectives of gas medium and E-field conditions,and the self-breakdown stability of the gas switch was compared.The self-breakdown dispersion of the gas switch filled with 15% SF_(6)/N_(2) mixed gas was no more than 6%within the pressure of 0.06 MPa to 0.56 MPa,while the lowest value was 1.4%.The self-breakdown voltage dispersion remained within the range of 2%-4%when the electrically negative gas content in the SF_(6)/N_(2) mixed gas was less than 30%.Within the charging voltage range of less than 1800 V,by changing the time-domain variation speed of the E-field in the gap,the self-breakdown voltage dispersion could be reduced to 0.2%with the breakdown voltage of 242 kV,while the voltage on the high voltage electrode rising speed was 12.4 kV/μs.However,reducing the field non-uniform coefficient didn`t significantly improve the breakdown stability in the 15% SF_(6)/N_(2) mixed gas at 0.3 MPa,but the self-breakdown voltage dispersion was still kept below 1%when the voltage rising speed increased on the high voltage electrode.By replacing the wedge-shaped trigger electrode with a groove-shaped trigger electrode,the minimum self-breakdown voltage dispersion could be as low as 0.15%,and the breakdown voltage was stabilized around 248 kV.