Simulation of Corona Discharge Process in Multistage Gas Switches Using VORPAL

The corona discharge process in a point-plane structure has been simulated using the 3-D particle-in-cell code VORPAL. The motivation behind these simulations was to understand how the corona needle worked in the gas switch, and to look for the methods to improve the stability of the gas switch by achieving a steady corona discharge. The influences of three parameters on ionization region were investigated, the needle size, the gas pressure, and the voltage applied across the electrodes. The needle size varied from 0.05 to 0.25 mm, the air pressure varied from 1.0 to 3.0 atm and the applied voltage varied from 1.2 to 2.3 kV. The voltage polarity was also changed. From the simulations, we obtained the electric field distribution, the distribution of the ionization region, and the current-voltage characteristic. All these parameters have an effect on the corona. Different voltage polarity would result in a different corona shape. Unlike the voltage polarity, the needle size, the air pressure, and the applied voltage have no effect on the shape of the corona. However, with an increase in needle size, or applied voltage, the corona size will also increase, while the corona size will decrease when the air pressure increases. The degree of influence is different; that of the applied voltage is the highest followed by the needle size, while that of the air pressure is the lowest.