Dielectric Electrode Surface Effects on Atmospheric Pressure Glow Discharges in Helium

Comparative experimental and theoretical studies are carried with 0.5-mm gaps using metallic and dielectric electrodes to examine the influence of dielectric surfaces upon the behavior of atmospheric pressure glow discharges in helium at frequencies of up to 22 kHz. The charge transfers associated with the discrete discharge current pulses exhibit a direct proportionality to the difference between the breakdown V_b and residual V_r voltages. The introduction of dielectric surfaced electrodes markedly increases the magnitude of V_r, which leads to substantially lower discharge currents. The calculated ionic and electronic charge carrier components comprising the discharge current pulses were found to be approximately equal when both electrodes were either metallic or dielectric. With one electrode metallic and the counter electrode dielectric, the electronic charge carrier component magnitude exceeded that of the ionic one by a factor of 2 in the positive half cycle.