Experimental study on self-pulsing in flow-induced atmospheric pressure plasma jet

In this paper, we present an experimental study on the self-pulsing phenomenon in a flow-induced atmospheric pressure plasma jet (APPJ) in a hollow electrode configuration driven by dc voltage supply. The current-voltage curve, the typical waveforms of current and voltage of self-pulsing, the time-resolved images, and the repetition frequency were measured under different experimental conditions. The results show that the APPJ of a hollow electrode can sustain in a stable, repeatable self-pulsing regime. The waveform of the pulsed current is very stable with nearly constant rising time and decay time at different discharge averaged currents. Although the pulsing frequency increases linearly with the averaged current and the gas flow rate, it decreases with the electrode gap. An equivalent electric circuit consisting of a capacitor and two resistors was used to model the self-pulsing discharge plasma. The simulation results and the time-resolved images recorded using an ICCD camera show that the pulsed process of the hollow electrode APPJ contains the evolutions of gas breakdown, discharge development, and decay of a glow plasma. A weak discharge is maintained during the time interval between two pulses, indicating that the self-pulsing in this APPJ is a mode transition between glow and weak discharge.