MODELING A COLLISIONAL, CAPACITIVE SHEATH FOR SURFACE MODIFICATION APPLICATIONS IN RADIOFREQUENCY DISCHARGES

Starting from previous analytical theories of the plasma sheath of an (rf) excited molecular discharge, we introduce an extension of these theories for the whole pressure range from the collision-free up to the collision-dominated sheath, including the region between these extremes. Collisions of the ions are taken into account via a viscous drag fluid model, leading to a set of integral equations. They are solved numerically using a fast-converging iteration scheme. The time-average potential distribution, electric field, sheath length, and ion and electron distribution within the sheath are obtained.