LAUSR

Using two water electrodes, a micro-gap dielectric barrier discharge excited by a saw-tooth voltage is investigated in atmospheric pressure argon. Through electrical and optical measurements, it is found that, at a lower driving frequency, a stepped discharge mode is obtained per half voltage cycle. Moreover, the duration and amplitude of the current plateau increase with the increase in the applied peak voltage. With the increase in the driving frequency, the stepped discharge mode transits into a pulsed one after a multi-peak mode. During this process, a diffuse discharge at a lower frequency transits into a filamentary one at a higher frequency. Temporal evolutions of the discharges are investigated axially based on fast photography. It is found that the stepped mode is in atmospheric pressure Townsend discharge (APTD) regime. However, there is a transition from APTD to atmospheric pressure glow discharge for the pulsed mode. Spectral intensity ratio of 391.4 nm to 337.1 nm is used to determine the ave...