Comparison of Annular Surface Dielectric Barrier Discharge Characteristics Under AC and Nanosecond Pulsed Excitation

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To explore the discharge characteristics of annular surface dielectric barrier discharge (SDBD) and guide the optimization of plasma excitation sources, this study presents a comparative analysis of SDBD behavior driven by a high-frequency, high-voltage alternating current (ac) power supply and a nanosecond pulsed power supply. The voltage–current waveforms and discharge images were employed to systematically investigate the differences in discharge initiation, spatial morphology, and temporal evolution under the two excitation modes. The results show that nanosecond-pulsed SDBD exhibits reverse discharge during the voltage fall phase, whereas ac-driven SDBD exhibits an earlier discharge onset due to cumulative surface charge effects. As the voltage amplitude increases, both excitation modes produce more streamer channels and broader discharge areas. However, their discharge distribution modes differ significantly. Annular SDBD under ac excitation produces filamentary discharge localized along the edge of the high-voltage electrode, whereas under nanosecond pulse excitation, the separated-channel discharge channels are produced. These differences are attributed to variations in voltage rise time and surface charge dynamics. Nanosecond pulses create a stronger transient electric field, expanding discharge coverage. In ac-SDBD, residual electrons near the high-voltage electrode promote early breakdown in the next cycle. In contrast, reverse discharge under pulsed excitation reduces residual positive charge and delays the next discharge. Nevertheless, the high conductivity of established channels promotes repeated breakdown in the same location, maintaining separated-channel distribution.