Numerical study of helium atmospheric pressure plasma jet interacting with a wavy substrate surface with different dielectric constants and curvature radius

Abstract

In this paper, we present a two-dimensional numerical study on a helium atmospheric pressure plasma jet interacting with a wavy substrate surface, focusing on the effects of the substrate relative dielectric constant and substrate morphologies on the plasma jet behavior near the wavy surface. The results show that when the dielectric constant is small, the jet can form separate discharge channels near the wavy substrate surface and can penetrate the cavity of the wavy substrate surface. With increasing dielectric constant, the penetration distance of the discharge channels decreases. When the substrate dielectric constant exceeds a certain value, the plasma jet only propagates above the wavy substrate surface and there are no prominent separated channels near the surface. Meanwhile, the radial propagation distance along the substrate surface decreases. For a certain dielectric constant, the penetration depth of the separated channel depends on the curvature radius of the wavy substrate surface and there exists a minimum curvature radius that allows the separated channel to enter the cavity. This minimum curvature radius varies with the substrate dielectric constant. If the dielectric constant becomes larger, the minimum curvature radius increases.