PLASMA-SHEATH BOUNDARY IN PLASMAS CONTAINING THERMAL AND BEAM ELECTRONS

The behaviour of the plasma-sheath boundary in the presence of beam electrons with finite temperature is modelled assuming a criterion for sheath formation. Solutions for the sheath edge potential are found from two separate treatments; a charge balance model and a dispersion relation description of the plasma. Ion saturation currents and floating potentials are determined as a function of the beam-plasma parameters. The results of this investigation can be used to predict the plasma properties at the surface of a substrate in process plasma discharges containing thermal electron beams.