Physical mechanism of positive and negative streamers propagation in packed-bed dielectric barrier discharge with pin-plate electrodes in air: A simulation investigation

The present study introduces a two-dimensional fluid model of packed-bed dielectric barrier discharge (PBDBD) in air at atmospheric pressure, aiming to investigate the streamer inception and propagation mechanism of PBDBD driven by positive and negative polarity nanosecond pulses. It investigates and interprets the distinct discharge characteristics exhibited by positive and negative streamers. Due to the polarization effect of the dielectric bead, positive charges accumulate on the upper surface of the dielectric bead for the positive streamer, while negative charges accumulate on the lower surface. Conversely, for the negative streamer, the charge distribution is reversed. Furthermore, regardless of the polarity of voltage, the charge polarity deposited near the vertex of the upper surface of the dielectric bead is opposite to the polarity of the surface of the hemisphere upon which it is situated and the same holds true for the vertex of the lower surface. It is worth noting that, unlike surface dielectric barrier discharge, the gas temperature rise effect is more pronounced for the positive streamer in PBDBD, leading to more intense pressure waves. As the peak value of pulse voltage increases, the gas temperature rises more rapidly. This study also finds a unique phenomenon only in the negative streamer, characterized by the presence of “side streamers” on both sides of the needle tip.