Experimental study of atmospheric pressure glow discharge

The atmospheric pressure glow discharge (APGD) is a new type of the discharge discovered by OKAZAKI et al. [1] recently. The APGD can be used in practical application (e.g. ozone generation), but the phenomena occurring in the discharge are not fully understood. We studied the APGD driven at 50 Hz, applied voltage up to 5 kV and burning in helium, argon and nitrogen. We used a planar configuration of discharge cell: metal electrode - dielectric plate (1 mm thick) - discharge gap (1.5 mm thick) - dielectric plate - metal electrode. Between the metal electrode and the dielectric plate a fine metal mesh was placed. For each gas we recorded the time dependence of power supply voltage and the time dependence of charge transferred through the discharge. We recorded also the discharges by the CCD camera with a video recorder. The same measurements were done in case of the discharge cells without the metal mesh. The metal mesh changes the discharge significantly. In the case of discharge cell with the mesh we can observe a homogeneous discharge and only one peak in the discharge current per half cycle of applied voltage while in the case of the discharge without mesh we observed individual micro-discharges and many pulses in the current per half cycle. This effect is most obvious in helium. In order to explain the observed phenomena we calculated the electric field in the discharge cell for APGD and propose a possible explanation of APGD. It has been found that the mesh does not influence the electric field in the discharge gap. Thus we propose that the mesh could influence the discharge by its electrical resistance, which is higher than the resistance of the metallic electrode.