Influence of Penning Ionization on Glowlike Dielectric Barrier Discharge Formation in Medium-Pressure Ar

Abstract

We experimentally investigated the influence of Penning ionization on glowlike discharge formation in Ar/C2H4 mixtures. The discharge was generated in a typical dielectric barrier discharge reactor with parallel-plate electrodes driven by sinusoidal voltage with a frequency of 100 kHz. The addition of a small amount of C2H4 caused the decrease of breakdown voltage. Excess C2H4 again increased the breakdown voltage since electron energy was reduced by the inelastic collision of C2H4. In the present case, the optimum amount of C2H4 addition was 0.07%. With increasing gas pressure, filamentary discharge appeared simultaneously in glowlike homogeneous discharge. The upper pressure limit to obtain the glowlike homogeneous discharge was improved from 220 Torr in Ar to 310 Torr in Ar/C2H4 (0.07%) because of the Penning effect. The temporal variation of Ar(1s5) density was observed by laser absorption spectroscopy. The density of Ar(1s5) coincided with the current waveform. C2H4 addition decreased the Ar(1s5) density because Ar(1s5) was consumed by Penning ionization. The reaction rate coefficient between Ar(1s5) and C2H4 was roughly estimated to be 10-9–10-10 cm3 s-1.