Semianalytical ion current model for radio-frequency driven collisionless sheaths

Abstract

We propose a semianalytical ion dynamics model for a collisionless radio-frequency biased sheath. The model uses bulk plasma and electrode boundary conditions to predict the ion impact energy distribution and electrical properties of the sheath. The proposed model accounts for ion inertia and ion current modulation at bias frequencies that are of the same order of magnitude as the ion plasma frequency. A relaxation equation for ion current oscillations is derived, which is coupled with a damped potential equation in order to model ion inertia effects. We find that inclusion of ion current modulation in the sheath model shows marked improvements in the predictions of the sheath electrical properties and ion energy distribution function.