Successive Multi-microdischarges Occurring in Pin-to-Line Geometry of Dielectric Barrier Discharge

Dielectric barrier discharges (DBDs) bring a long history of application and leave many interesting scientific questions. A positive streamer concept describes a temporal development of a microdischarge well, and memory charge effect explains spatially distributed microdischarges over the entire area of DBD. To properly model plasma chemistry occurring in a DBD, knowledge of microdischarges, distributed spatially and temporally, is essential. Here we present experimental result of multiple microdischarges, occurring successively and rooted at the same location. By employing a triangular waveform to a pointed electrode and a high conductivity layer at a surface of a dielectric barrier, a physical mechanism of the successive microdischarges was revealed: a slew rate of an external alternating current compensated a voltage drop caused by memory charges from a former microdischarge. A time interval between two neighboring microdischarges was inversely proportional to the slew rate, and the number of microdischarges depended primarily on an applied voltage. The number of microdischarges with an uncoated barrier was higher than that with an Ag-coated barrier; however, the charges delivered by each microdischarge were smaller in cases with an uncoated barrier. To investigate interactions between spatially separated microdischarges, this study will be extended to a configuration having multiple pointed electrodes. The effect of the successive microdischarges on plasma chemistry will also be a future study.