Kinetic analysis of direct-current driven microdischarges with thermo-field electron emission at atmospheric pressure

Recent studies have shown that thermo-field emission is a dominating electron source in microdischarges at the cathode temperature far above room temperature. However, few researches focus on the post-breakdown nature of microdischarges. In order to explore the post-breakdown characteristics of thermo-field emission driven microplasma, a one-dimensional implicit Particle-In-Cell with Monte Carlo Collision method is adopted and updated by considering the thermo-field electron emission to investigate the kinetic characteristics of direct-current argon microdischarges at atmospheric pressure. The fundamental properties of the microplasmas, such as electric field, particle number density, averaged particle temperature and current density, are analyzed in the post-breakdown regime. In addition, the sheath behavior is investigated to further observe how the space charge affects the thermo-field emission. The results indicate that thermo-filed emission driven micro-scale discharges can produce high current density and high-energy particles with low applied voltage of 20V. The impacts of cathode temperature on enhancing the thermo-field emission are more pronounced compared to the applied voltage and the electrode spacing. The electron energy probability function shows a multi-peak distribution.