On the pulsed-pulseless mode transition of negative DC corona in atmospheric nitrogen

Pulsed mode as a common phenomenon appears in many kinds of DC corona discharge, whose characteristics can be affected by some specific factors. In this paper, an important research field of pulsed mode, pulsed-pulseless mode transition, is investigated in needle-plate electrodes in nitrogen at atmospheric pressure, and we discuss the effect of external circuit, gas temperature, and associative ionization on mode transition by experiment and simulation. The external circuit coupling with plasma can make the pulseless mode be achieved when there is a balance of charge between loss by discharge and gain by source before discharge quenches. The time-averaged gas temperature remains at 700 K which is regardless of source voltage and discharge mode, so gas heating is not a critical factor for mode transition. We investigate the effect of the associative ionization involving metastable particles by comparing the results with and without associative ionization reactions in the simulation; we find that the associative ionization is vital to determine the cathode voltage, discharge current, and the concentrative shape of discharge in the pulseless mode. Finally, we compare the pulsed-pulseless mode transition in nitrogen and air to clarify the effect of specific factors that depend on electronegativity of gas.