Surface Charges in a Coplanar-Electrode Microgap Discharge Measured at Various Gas Pressures Using an Electrooptic Crystal

Abstract

The surface voltage and charge on the dielectric barrier in a plasma display panel (PDP)-like microdischarge have been measured using an electrooptic crystal. The initiation of discharge starts the accumulation of surface charges and the charges spread uniformly over the entire region of the electrode surface under the condition of a time resolution of 0.1 µs. For the case of a gas mixture of Ne+Xe (10%), the plasma light emission at the cathode side is much stronger than that at the anode, however, the quantity of surface charges accumulated at both electrodes are the same. The surface charges at various gas pressures are also measured as functions of externally applied voltage and total charge flowing in an external circuit estimated from the discharge current. These characteristics for the microdischarge are compared with the results obtained for macrodischarge. It is found that the voltage difference on the barrier surface between the ground and high-voltage electrodes, caused by the accumulated charges, is an important factor in determining the barrier discharge.