Numerical analysis of plasma formation process in a coaxial dielectric barrier discharge

Plasma formation process in a coaxial dielectric barrier discharge (coaxial DBD) device was analyzed by numerical simulations based on plasma fluid modeling. Helium plasma in the coaxial DBD is formed through three stages of Townsend-glow, streamer, and surface type discharges. Through the three stages, the plasma electron density becomes high not only between the electrodes, but also in the vicinity of the dielectric surface. Differences between coaxial and planar type DBDs are also discussed. The presence of the dielectric surrounding the plasma in the coaxial DBD device is thought to induce a non-uniform distribution and a transition to surface discharge, resulting in multiple discharge modes.