Research on gas spark switch for high power laser system

By comparing three candidate high current and high coulomb gas switches-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.