Transition of streamer, corona and glow discharges in needle-to-plane dielectric barrier discharge at atmospheric pressure air

To discuss the modes of dielectric barrier discharge (DBD) between needle-to-plane electrodes in air, DBD is generated and observed on a needle-to-plane device at atmospheric pressure air. Fast images of the DBD are taken by using a charge couple device (CCD) cinema with a macro lens, while the electrical and photo-electricity waveforms of the DBD are recorded. The current waveforms show that under an applied voltage of 3 kV, there are numerous short current pulses in both positive and negative half-periods of discharges. However, under 6 kV, there are still the numerous short current pulses in the positive half-periods, but only one wide current pulse in each negative half-period. This difference is also found in the photoelectric signals. The streamer, corona and glow discharges are observed from the images of the discharges at different applied voltages. The structure of glow discharge in the negative period is exactly the same as that of the low pressure glow discharge. However, in the positive period of discharge there is always a streamer. In the negative period of discharge, while the applied voltage increases, the transition from corona to glow discharge is observed. The progress of a transition between streamer and glow discharge at 6 kV during one period is analyzed. The glow discharge appearance is determined by two factors: the discharge current is limited to a certain extent by the dielectric layer; the charges deposited on the dielectric layer during the last half period enhance the intensity of the electric field. At an insufficient applied voltage, the cathode drop leads to no glow discharge, but Trichel pulses.