Numerical Study on Collision-Less Plasma Sheaths of RF-Glow Discharge

Abstract

Abstract A self-consistent mathematic model for radio frequency (RF) glow discharge was proposed to investigate the spatiotemporal evolvement of collision-less plasma sheaths at different plasma characteristics, in which the influences of ion motion by instantaneous sheath electric field were considered and the present model would be suitable for describing the spatiotemporal characteristics plasma sheaths with wide RF-frequency ranges. The instantaneous relationship between the voltage on the RFbias electrode and the sheath thickness was determined by an equivalent circuit model coupled with a fluid model. The periodic distributions of voltage on RF-bias electrode, sheath thickness, sheath electric field, density of ion and electron in sheath were obtained by numerical methods based on the present model. It was found that the distribution of electrode voltage presents nonsinusoidal waveform which is different from the sinusoidal waveform assumptions of other researches. The numerical computation results show that β, the ratio of RF frequency and ion plasma frequency, is an important parameter that affects RF plasma sheath's features: the motion and density distribution of ion are mostly controlled by instantaneous sheath electric field if β 1, the ion motion could be determined by the average field intensity of plasma sheath, and the ion density could almost not be changed.