Control of diffuse and filamentary modes in an RF asymmetric surface barrier discharge in atmospheric-pressure argon

The controlled generation of diffuse and filamentary modes is demonstrated in a radio-frequency (RF, 13.56MHz) asymmetric surface barrier discharge in atmospheric-pressure argon. For both continuous and pulsed input power, it is shown that the transition from a streamer-driven filamentary discharge at breakdown to a low-current, diffuse plasma can be attained. Fast imaging is used to visualize the structure of the discharge and examine the transition between three distinct modes: moving filaments, branching filaments and a filament-free plasma. The breakdown of the pulsed discharge is studied for pulse periods ranging from 5s to 1ms to investigate the mechanism behind the generation of the diffuse mode.