Study of surface charges on dielectric electrodes in a radio-frequency glow discharge

A radio-frequency glow discharge between dielectric electrodes is observed by spatiotemporal optical emission spectroscopy. No emission from an excited Ar ion is observed in the dielectric electrode discharge, but it is observed in a discharge with metallic electrodes under the same external conditions. On the other hand, marked excitation of Ar(3p₅) on the driven dielectric is observed. The maximum of the spatiotemporal net excitation rate profile is larger and the amplitude of the current is smaller compared with the discharge sustained by metallic electrodes. These differences are attributed to the effect of surface charge on the dielectric. The dielectric immersed in the discharge is exposed to the ion and electron fluxes, and is charged negatively to balance both fluxes. The accumulated charge on the dielectric is estimated by a capacitor in series with the grounded electrode. As a result, the surface charge affects the field just in front of the dielectric and enhances excitation and ionization.