气体开关串级环形间隙放电相互影响机制研究

针对中空和非中空触发电极结构的两间隙开关，进行了触发击穿特性实验，对比两个间隙的击穿抖动和通道数，分析了串级两间隙的相互影响机制。实验结果表明：两只开关触发间隙击穿抖动和通道数变化规律基本一致；非中空开关自击穿间隙击穿抖动随工作系数的增大而减小，最小约3 ns，中空开关自击穿间隙击穿抖动始终约1 ns；非中空开关自击穿间隙难形成多通道放电，中空开关自击穿间隙通道数明显多于其他间隙。触发间隙首先放电产生紫外光，通过触发电极中空通孔预先照射自击穿间隙产生初始电子，是自击穿间隙击穿抖动减小、通道数增加的主要作用机制。     

气体开关触发间隙与过压间隙击穿特性研究

为研究快脉冲直线变压器驱动源（FLTD）多间隙气体开关的触发击穿特性，针对一种环形电极两间隙等效实验开关，开展不同触发电压、工作系数和电极材料下的击穿特性实验，对比两个间隙的击穿延时和抖动，分析间隙击穿特性的主要影响因素和作用机制。实验结果表明：触发间隙击穿延时主要受触发电压影响，而工作系数是过压间隙击穿延时的主要影响因素；开关抖动主要来自于触发间隙，触发间隙抖动随触发电压的增大明显减小，过压间隙抖动基本不随触发电压和工作系数变化且维持在较低值；石墨电极开关的击穿延时和抖动明显小于不锈钢、黄铜和钨铜电极开关，具有良好的触发击穿性能。通过分析指出，是否有预电离可能是两个间隙击穿特性差异的主要原因。     

Experimental investigation on the development characteristics of initial electrons in a gas pressurized closing switch under DC voltage

As one of the most important elements in linear transformer driver(LTD) based systems, the gas pressurized closing switches are required to operate with a very low prefire probability during the DC-charging process to ensure reliable operation and stable output of the whole pulsed power system. The most direct and effective way to control the prefire probability is to select a suitable working coefficient. The study of the development characteristics of the initially generated electrons is useful for optimizing the working coefficient and improving the prefire characteristic of the switches. In this paper an ultraviolet pulsed laser is used to generate initial electrons inside the gap volume. A current measuring system is used to measure the time-dependent current generated by the growth of the initial electrons so as to study the development characteristics of the electrons under different working coefficients. Experimental results show that the development characteristics of the initial electrons are influenced obviously by the working coefficient. With the increase of the working coefficient, the development degree of the electrons increases consequently. At the same times, there is a threshold of working coefficient which produces the effect of ionization on electrons. The range of the threshold has a slow growth but remains close to 65% with the gas pressure increase. When the working coefficient increases further, γ processes are starting to be generated inside the gap volume. In addition, an optimal working coefficient beneficial for improving the prefire characteristic is indicated and further tested.     

Comparative study on breakdown characteristics of trigger gap and overvoltage gap in a gas pressurized closing switch

Gas pressurized closing switches are one of the most important elements in FLTD-based systems. Improving the trigger performance of gas switches is useful for optimizing the output parameters and the reliability of the FLTD. In this paper, the breakdown characteristics of the trigger gap and the overvoltage gap are studied experimentally. The reasons for the different breakdown performance of the two gaps are also investigated. The results show that the breakdown delay of the trigger gap is more influenced by the trigger voltage, while the breakdown delay of the overvoltage gap is more influenced by the working coefficient and always higher than that of the trigger gap. The jitter of the trigger gap is more influenced by the trigger voltage and accounts more than 60% of the total switch jitter, while the jitter of the overvoltage gap is hardly changed with the trigger voltage as well as the working coefficient and maintains less than 1.4 ns. It is proved that the discharging product from the trigger gap can effectively reduce the breakdown delay and jitter of the overvoltage gap. Based on that, the effect and improvement of pre-ionization on the two gaps are also studied. It is concluded that the jitter of the trigger gap reduces obviously when the pre-ionization is added, while the pre-ionization almost has no effect on the jitter of the overvoltage gap. The jitter of the overvoltage gap is about two times higher than the trigger gap in the pre-ionizing switch.