Multiple current pulse behavior and its dynamics of atmospheric pressure plasma jet in a needle-to-ring configuration

The characteristics of an atmospheric pressure plasma jet (APPJ) based on needle-to-ring dielectric barrier discharge (DBD) have been investigated experimentally. The plasma jet is driven by a sinusoidal voltage, and the working gas is argon. The jet length, the voltage-current waveforms, the optical emission spectra and the plasma evolution have been studied. Moreover, the transferred charges of the discharge pulse and the electron excitation temperature were investigated. These results reveal that there exist two or more current pulses per half-cycle as the applied voltage increases. In fact, the multiple current pulses correspond to multiple breakdowns between the electrodes. This phenomenon in DBD-APPJ is mainly attributed to the surface charges on the grounded ring electrode surface, which can induce a strong reverse electric field to counteract the applied electric field. In addition, the jet length is extended stepwise as the number of current pulses increases. The residual excited species or charges remaining from the previous discharge play an essential role in the formation of a stronger next discharge and are responsible mainly for a higher electron excitation temperature, which makes the jet develop farther (i.e., a longer jet). Finally, we obtain a preliminary control condition to switch a single current pulse into multiple pulses, which has a benefit for industrial applications.