Pulse Repetition Rate Characteristics of Microwave Plasma Interference Switch With Plate and Pin Electrodes

—This article is a simulation and experimental investigation of microwave plasma interference switch (MPIS) with plate and pin electrodes. A 2-D coupled self-consistent MPIS model is established to simulate the generation process of the plasma with initial electrons in MPIS under microwave heating. The simulation results show that the plate electrode MPIS is more difficult to self-breakdown and has a higher repetition rate due to the electron diffusion effect and different electric field strength at the electrode surface. An experimental study of MPIS with different electrode shapes, electrode positions, incident power, repetition rate, gas flow rate, dc voltage, and gas pressure was carried out to investigate the effect of different parameters on the MPIS repetition rate. The experimental results show that the electrodes should be set outside the waveguide and operated at atmospheric pressure with a high gas flow rate. Under atmospheric pressure, the incident power of 500 kW, the dc voltage of 10 kV, and the gas flow rate of 3000 sccm, the plate electrode MPIS was able to operate stably at a repetition frequency of 250 Hz without self-breakdown. Low pressure (4 kPa) and low dc voltage can decrease the occurrence of self-breakdown. The reflected waveforms of MPIS show that the self-breakdown has a wider rising edge compared to the triggered breakdown.