Simulation of a two-dimensional sheath over a flat wall with an insulator/conductor interface exposed to a high density plasma

Abstract

The structure of the two-dimensional (2D) sheath over a flat, electrically inhomogeneous wall exposed to a high density plasma was investigated by a fluid model. The wall consisted of a floating semi-infinite insulator in contact with a semi-infinite conductor biased by a negative dc voltage. The difference in sheath potential over the two materials resulted in a 2D sheath over the insulator/conductor interface. The ion flux was higher on the conductor side of the interface at the expense of the flux on the insulator side. The spatial extend and magnitude of the ion flux disturbance scaled with the difference in the sheath thickness over the two different materials. The ion impact angle along the surface increased progressively as the material interface was approached. Sheath distortion was exacerbated when the electron temperature was decreased or the bias potential was made more negative.