The streamer-to-spark transition in a transient spark: A dc-driven nanosecond-pulsed discharge in atmospheric air

摘要

We present a study of the streamer-to-spark transition in a self-pulsing dc-driven discharge called a transient spark (TS). The TS is a streamer-to-spark transition discharge with short spark duration (10100ns), based on charging and discharging of the internal capacity of the electric circuit with repetition frequency 110kHz. The TS can be maintained under relatively low energy conditions (0.11mJpulse ~1). It generates a very reactive non-equilibrium air plasma applicable for flue gas cleaning or bio-decontamination. Thanks to the short spark current pulse duration, the steady-state gas temperature, measured at the beginning of the streamers initiating the TS, increases from an initial value of 300K only up to 550K at 10kHz. The streamer-to-spark transition is governed by the subsequent increase in the gas temperature in the plasma channel up to 1000K. This breakdown temperature does not change with increasing repetition frequency f. The heating after the streamer accelerates with increasing f, leading to a decrease in the average streamer-to-spark transition time from a few s to less than 100ns.