Coaxial rf atmospheric pressure dielectric barrier air-helium plasma characteristics

The electrical and optical characteristics of a coaxial rf atmospheric pressure dielectric barrier discharge (DBD) with one electrode covered with glass and with helium in air were investigated. Optical measurements with an intensified charge coupled device (ICCD) camera combined with the voltage and power vs. current data provided identification of the alpha to gamma mode transitions. The coaxial design allowed operation with very low power density plasmas (0.18 W/cm(3)) and a much larger plasma size (13 mm) than the parallel plate designs. (C) 2011 Elsevier B.V. All rights reserved.