Simulation on the arrayed microhollow cathode sustained discharges
The spatiotemporal dynamics of arrayed microhollow cathode sustained discharge(MCSD)are simulated using a fluid model in this study.In particular,the dependence of discharge currents on different electrode surfaces on microscopic plasma parameters such as charged particle density and electric field are investigated in detail.The simulation results reveal that the discharge is divided into four stages with increasing cathode current.The first stage is a Townsend-like discharge wherein the discharge currents on three electrodes,and the space charge densities and electric field are extremely low.The second stage is the breakdown stage of the discharge in the cavity,in which the discharge in the cavity breaks down and a clear hollow cathode effect appears.The discharge currents on the two MHCD electrodes,density of charged particles in the cavity,and electric field increase rapidly.However,the anode(first anode)in the MHCD electrode remains in the anodic role,and the discharge between the MHCD and third electrode(second anode)is not broken down.In the third stage,discharge in the space between the MHCD and third electrode gradually breaks down,and the direction of the currents on the surfaces of the cathode and the first anode in MHCD is identical.The first anode gradually changes from an anode to a cathode,forming a cathode sheath layer around the first anode.The charged particle density in the MCSD discharge space increases rapidly.The fourth stage is the steady-state phase of the discharge,in which a stable arrayed MCSD is formed,and the quantitative relationship between surface currents of each electrode in the MCSD discharge structure is satisfied.Furthermore,in addition to the MHCD discharge,the third electrode glow discharge plays a crucial role in promoting the formation of the MHCD and MCSD discharge.The arrayed MCSD is formed by the combined effect of the MHCD and third electrode glow discharges.