Diffuse and Filamentary Discharges in Open Air Driven by Repetitive High-Voltage Nanosecond Pulses

Nanosecond repetitive pulsed discharge in atmospheric air has attracted significant attention due to its fast rise time and short duration in various applications. With an excitation of unipolar repetitive pulses of 25-ns rise time and 40-ns duration, diffuse discharge in open air is obtained in a tube-plane gap. The discharge photographs show the transition of the discharge forms from diffuse to filamentary discharge in response to the decrease of the air gap spacing.