Characterization of a pulsed-DC capillary dielectric barrier discharge as a cold plasma source for atmospheric pressure applications

We report on the development of an atmospheric pressure plasma jet (APPJ) in a dielectric capillary arrangement using submicrosecond unipolar pulsed-DC excitation as a source for generating a stable, nonequilibrium plasma . This APPJ source differs from other arrangements in that the plasma jet is a self-sustained streamer-like discharge rather than the flow-driven plasma effluent from a discharge within the capillary. We examine the characteristics of this APPJ device in two operating modes. In an open-air configuration, the device runs in a low current streamer discharge mode characterized by a visible plasma jet with a length of ~3.5 cm using a 12 kV voltage pulse and a repetition rate of 1 kHz with an Ar/He flow gas. This APPJ device can be operated with a single powered electrode terminated into a virtual ground plane. With the addition of a physical external cathode, a thin transient discharge filament forms along the capillary axis from which several Amps of current can be drawn. In this closed configuration, the discharge can be described as a spatially confined capillary dielectric barrier discharge of limited duration. We will show results using electrical measurements and spatiotemporally-resolved optical emission and gated ICCD imaging to characterize this APPJ source.