Mode transition and plasma characteristics of nanosecond pulse gas–liquid discharge: Effect of grounding configuration

摘要

Transitions between the streamer and spark modes affect the stability of gas-liquid discharges, limiting their practical applications, while the nature of such transitions is poorly understood. Here we clarify the often neglected effect of a dielectric on the gas-liquid discharge stability, using direct and indirect grounding configurations. Discharge modes and plasma characteristics in these two configurations are investigated. The discharge appears in a transient spark mode in the direct grounding while in a streamer mode in the indirect case. It is shown that the dielectric significantly improves the discharge stability. The gas temperature and electron density in the transient spark are 380 K and 10(17)/cm(3) with a 30 kV pulse voltage, respectively, which are higher than those in the streamer mode.