Impact of Residual Surface Charges on Energy Coupling of Packed-Bed Dielectric Barrier Discharge: A Simulation Investigation

Packed-bed dielectric barrier discharge (PB DBD) is a promising reactor for plasma catalysis, while the charge accumulation on the dielectric surface significantly affects the discharge dynamics and plasma chemistry. In this work, the role of residual surface charges in PB DBD reactor driven by repetitively high-voltage (HV) pulse with different polarities and pulse sequences is investigated, based on a two-dimensional fluid model. For the positive pulse, both charge transfer and energy deposition are elevated with negative HV as the previous pulse (i.e. bipolar mode), while they are suppressed with unipolar pulses. However, for negative polarity, the intense charge accumulation greatly enhances energy deposition regardless of operating modes, which is due to that a sufficient field enhancement caused by residual surface charges can directly lead to the breakdown between the packing beads gap, and thus promotes the discharge. The presence of residual surface charges alters the electric field distribution at the streamer front and plasma channel, regulates the percentage of power density deposited in these regions, and further dictates the energy branching into different processes. The results in this work illustrate the regulation effect of residual charges on the energy coupling of the PB DBD, which is beneficial to specifically improve the plasma-catalysis performance.