Theoretical and Experimental Analysis of a High Pressure Glow Discharge Controled by a Dielectric Barrier

Abstract

Recently many experimental works have been devoted to the study of an atmospheric pressure glow discharge controled by a dielectric barrier^1,2. There is a strong evidence that this type of discharge works well in pure helium. for other gases it seems to be necessary to introduce an additive (for example acetone in argon) in order to obtain a glow discharge or, in other situations (for example in air), small metallic mesh grids must be added inside the dielectric walls. Our experimental work, associated with our theoretical calculations³ showed that, in helium, a glow discharge can only be obtained if there is a small amount of impurity inside the gas. the main role of these impurities (N₂ for example) is to allow, through the various metastable levels of helium, an increase of the ionization mainly in regions in which the electric field is so low that it cannot produce direct ionization of the molecules. It is clear then from these considerations that a glow discharge cannot occur in very pure helium in which the amount of impurities is too low.