Plasma sheath model and ion energy distribution for all radio frequencies

The spatiotemporal structure of the sheath and the ion energy distribution (IED) at the electrode of a collisionless electropositive glow discharge we re studied with a model that is valid for arbitrary radio frequencies (rf). The model is based on the work of P. A. Miller and M. E. Riley [J. Appl. P hys. 82, 3689 (1997)] and uses an effective electric field to which the hea vy ions respond. Given the plasma density and electron temperature at the s heath edge, and the waveform of either the potential or total current acros s the sheath, the spatial and/or temporal profiles of the following quantit ies were obtained: sheath thickness and capacitance, electron and ion densi ties, potential, and individual components of the current. An analytic expr ession for the energy split of the IED function was also obtained. The prod uct omega tau(i) of applied radian frequency omega and ion transit time tau (i) is a critical parameter for describing the sheath dynamics. (C) 1999 Am erican Institute of Physics. [S0021-8979(99)02207-0].