Numerical Study Of Pulsed Dielectric Barrier Discharge At Atmospheric Pressure In The Needle-Plane Electrode Configuration

In recent years, with the development of pulse generator, the dielectric-barrier-discharge (DBD) at atmospheric pressure driven by unipolar or bipolar high-voltage pulse has developed rapidly. Many studies have shown that compared with the discharge driven by sinusoidal voltage, the pulsed DBD has immense potentials for numerous industrial applications including materials processing, biological and chemical decontamination of media, etc. The needle-plane pulsed DBD with low breakdown voltage and strong discharge has shown its unique advantages in material treatment for a rough surface or a small area. At atmospheric pressure, the needle-plane DBD is generally corona discharge or streamer discharge. However, some experimental results have shown that under certain condition the needle-plane DBD can operate in a uniform discharge mode. In particular, after the plate electrode is covered by a thin dielectric layer, the uniform pulsed DBD in needle-plane geometry can be obtained over wide parameter range. At present, the investigations on the needle-plane DBD are almost limited to the observation of experimental phenomena, there is no clear understanding of the discharge evolution, the discharge mechanism, as well as the influence of discharge parameters on the discharge behavior. In this paper, we study the characteristics of atmospheric-pressure pulsed DBD in the needle-plane configuration using a one-dimensional self-consistant fluid model. The finished studies include the following two sections:In section one, we study the characteristics of the needle-plane DBD driven by a positive pulsed voltage and the effect of the parameters on the discharge behaviors. The simulation results show that, in the needle-plane pulsed DBDs, there exist two discharges during a pulsed period, but the formation processes of these two discharges are different. In the first discharge, the discharge starts near the needle electrode, then propagates to the the instantaneous cathode, and eventually evolves into a glow discharge. In the second discharge, the discharge mainly occurs near the needle electrode and the discharge evolves from a sub-glow discharge to a normal glow discharge. The changes of the needle tip radius, the relative permittivity, and the thickness of dielectric layer mainly affect the behaviors of the second discharge. The pulse width, the rising time and falling time of applied voltage pulse have great effect on both two discharges, and when the falling time is too long, the second discharge will not occur. In section two, we study the behaviors of the needle-plane DBD driven by a negative voltage pulse and a bipolar voltage pulse, respectively. The simulation results show that the formation regime of the negative pulsed DBD are different from that of the positive pulsed DBDs. The breakdown voltage for the case of the negative pulse is much higher than that of the positive pulse. In the bipolar pulsed DBD, owing to the mutual effect between positive pulsed discharge and negative pulsed discharge, the behaviors of the bipolar pulsed DBD are different from that of the unipolar pulsed DBD. The negative pulsed discharge in bipolar pulsed DBD can occur at lower breakdown voltage. The mutual effect between positive pulsed discharge and negative pulsed discharge depends on the waveform and repetition frequency of the applied bipolar voltage pulse.