The influence of the cathode radius on the microgap breakdown in air based on PIC/MCC simulation

Traditionally, Paschen's Law is used to describe and predict the gas breakdown. However, more and more experiments have shown that the Paschen's Law fails when the gap dimensions fall below 10μm, and this new curve was known as the modified Paschen's curve. In this work, we proposed a simulation model based on the particle-in-cell/Monte Carlo (PIC/MCC) collisions method and calculated the breakdown thresholds with different cathode radii and gap distances in microgaps. Results show that the critical gap distances for the transition process and the "plateau" region varied with the cathode radius, and the relationship between the discharge process and the cathode radius, which demonstrates a good consistence with the experimental breakdown thresholds, and the series of simulation results has guiding significance for further research on the microscale dielectric breakdown theory.