Modeling of atmospheric pressure Helium discharges in extremely narrow gap

Recently, atmospheric pressure discharges have been applied on various fields, such as material surface modification. There are many methods for generating atmospheric pressure discharges, such as plasma jets, dielectric barrier discharges and so on. Among these plasmas, pulsed atmospheric pressure discharge plasmas in extremely narrow gap have been focused on for its characteristics of high plasma density generation and less loss of radicals. To simulate like these plasmas, using Monte Carlo method has advantage. For the first step, using Monte Carlo method to simulate these discharges, electron avalanches have been simply simulated in one dimension with narrow gap and highly applied voltage, and EEDFs had been examined. The discharges have been generated using fine cylinder and mesh electrodes with 10 micro meter gap and applied ~800V pulsed voltage to mesh electrode[1]. There are two regions to be taking into consideration. So two regions were simulated, one is open electrode region and the other is extremely narrow gap region. In the open electrode region, the electric field significantly decreases as moving away from the electrode, and it is found that EEDF at each location are slightly different from the one which is equilibrium. In extremely narrow gap region, electrons have swept away at lower applied voltage, and then electrons accelerate extremely high energy at a moment but absorbed in the electrode in extremely short time. The EEDFs become quite different from the equilibrium ones.