Numerical simulation of the breakdown process of micro-discharge sustained by field emission

Abstract Micro-discharge is the process that gas breakdown occurs on a small spatial scale to generate plasma. With the decrease of the discharge scale, the high electric field makes the field emission (FE) play a leading role in the breakdown process of the micro-discharge, which is one of the reasons that the breakdown voltage deviates from the Paschen curve in a small gap. A one-dimensional implicit particle-in-cell Monte Carlo collision model is used to simulate the whole breakdown process of direct current micro-discharge sustained by FE in argon. The results show that the discharge after breakdown is in arc mode, the breakdown process can be divided into three stages: the pre-breakdown stage, the breakdown stage, and the post-breakdown stage. In the pre-breakdown stage, the sheath and plasma are not formed, the external electric field can penetrate the entire gap. In the breakdown stage, gas breakdown occurs. As the sheath is formed, the rate of change of plasma parameters increases rapidly and the discharge gap changes from capacitive to resistive. In the post-breakdown stage, the anode sheath gradually becomes thinner, but the region where the field is reversed still exists. The particle and energy balance gradually reach equilibrium, and the entire discharge evolves to a quasi-steady-state.