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

Abstract

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