Experimental study of atmospheric pressure surface discharge in helium

The surface discharge generated at atmospheric pressure in helium was examined by monitoring the current and voltage atthe discharge electrode. The discharge generated in helium behaves differently when compared to that generated in other gases (e.g. air). The single discharge duration and the time between consecutive discharges are longer because there is a different mechanism of discharge evolution. The metastable helium atoms play the most important role for discharge generation. Streamer-like and glow types of discharge were observed. The decay of helium metastables concentration determines the discharge regime. Hence, operation conditions have strong influence on the discharge regime. The introduction of gas flow removes metastable quenchers /gaseous products from dielectric and electrode surfaces) and transition to glow discharge is observed. Also covering the discharge electrode with thin dielectric foil to suppress Auger de-excitation of metastables at metal surface leads to generation of atmospheric pressure glow surface discharge. Properties of this discharge are comparable with properties of glow discharge at low pressure (e.g. the electron concentration).