Simulation of mode transition and power matching in micro dielectric barrier discharges

Summary form only given. Recently, atmospheric pressure micro plasmas have attracted increasing interests for useful applications such as surface modification and bio-medical treatment. Among many atmospheric pressure plasma devices, a dielectric barrier discharge (DBD) is conventionally used to sustain a glow discharge within a short gap. However, experimental diagnostics of micro DBDs are limited due to the small size and highly collisional plasma properties. Thus, computer simulation is useful to understand the characteristics of DBDs under wide variations of driving conditions and geometry of the device. In this study, we report the investigation of micro DBDs using a fluid model and a particle-in-cell (PIC) simulation coupled with Monte Carlo collision (MCC). The one-dimensional PIC-MCC simulation code XPDP1 was adopted to investigate the discharge characteristics of a planar micro DBD with pure helium with a driving frequency from 13.56 to 474 MHz. It was found that the transition of different heating modes and power matching to external circuit are related to the ratio of ion transit time to the RF period. In addition, a two-dimensional fluid model and a PIC-MCC simulation were used to investigate the effect of electrode and dielectric surface shape as well as driving frequency in a coplanar discharge.