Calculation of electric fields for laser triggered multistage gas switch

To design intense pulsed electron beam accelerator, calculation of electric field is very important. This paper will introduce the use of the electric field codes in designing laser triggered multistage gas switch, which is the, key part of the intense pulsed electron-beam accelerator. This calculation use the SEF2D, a program based on two-dimension finite element method. A series of problems were solved effectively, such as multi-medium complicated structure with floating electrode in switch. An uniform electric field distribution across,the gaps and on the insulator surface have been achieved, with the average field approximately 260kV/cm and 55kV/cm respectively (for 1.4 MV operating voltage) Moreover; A breakdown process is studied with the method of electrostatic field simulation. It offered us the multiple of overvoltage and field enbencement for each stage of switch during closure. Then breakdown time of multistage switch is obtained by the calculation. The experiment results provided by subsequent text are agreed with the simulation well. So far, the switch works well at high voltage (1.2 MV), Gap closure time 50ns jitter less than 2ns have been achieved.