Discharge-Mode Transition in Jet-Type Dielectric Barrier Discharge Using Argon/Acetone Gas Flow Ignited by Small Helium Plasma Jet

A discharge-mode transition in a jet-type dielectric barrier discharge (DBD) was triggered by a small fraction of acetone vapor added to an argon (Ar) gas flow at atmospheric pressure. In order to trigger a stable discharge in the Ar/acetone gas flow with a relatively small applied voltage, we used an additional small plasma jet using a He gas flow on the side of the main flow. The transition from filamentary to glow like discharge modes took place upon increasing the acetone-vapor ratio, with the transition occurring at an acetone content of approximately 0.3 vol %. We compared discharge currents, optical emission spectra, and deposited materials on the substrate in each discharge mode to characterize the discharge phenomena. The experimental results clearly indicate that the characteristics of the jet-type DBD show nonlinear dependence on the acetone-vapor ratio, especially around the transition to the discharge mode. It was also found by microscopic observations that the surface morphologies of the deposited materials were completely different in the filamentary and glow like modes. (C) 2011 The Japan Society of Applied Physics