强激光能源系统用气体开关的研究

Research on Gas Spark Switch for High Power Laser System

针对强激光能源系统对开关元件的要求,在比较高库仑量大电流气体开关的3种主要类型:三电极场畸变开关、两电极同轴结构开关、旋弧开关后提出并研制了强激光能源系统开关定型上应优先考虑的两电极同轴结构开关。对开关电极材料的选取进行了理论和实验上的探讨,为了减少电极的烧蚀,需选择比热、密度、相变潜热大、熔点高的电极材料。理论分析和15 kV、200 kA下的开关样机实验结果表明,高密度石墨较为适合做大电流气体火花开关电极,电极材料的显微结构对开关电极的烧蚀和寿命影响较大。

By comparing three candidate high current and high coulomb gas swltches-three electrodes field-distortion switch, two-electrodes coaxial switch, arc rotary switch（ARG）, the two-electrodes coaxial switch is selected as the closing switch for high power laser system. The selection of the electrodes material is discussed on the basis of theories and experiments. A compact long-lived spark gap and a matched series-injection trigger generator have been developed. The spark gap is located at the centre of metal chamber, this kind of structure can prevent arc approach the insulated bracket. Elimination of the trigger electrode, used in many other switches, combined with an integral, coaxial current-return housing, allows the switch to handle very high current and charge transfer. Micrographs of erosion for a few of electrode materials are given. Analyses of the electrodes erosion of different materials indicate that high-density graphite is more suitable for electrode of the high current and high coulomb gas switch. The experimental results of the switch sample developed by this project with peak current 200kA, work voltage 15KV, transfer charge 50coul are presented and graphite electrodes of different grades are compared. The Micrograph of erosion indicates that the microstructure of the graphite has a great influence on electrode erosion and electrode life.