An indirect method for measuring the electron density of radio frequency atmospheric pressure plasma jets （RF-APPJ） based on the discharge voltage and current waveforms is presented. An equivalent circuit of the plasma discharge is assumed by taking into account the electrode capacitance, serial resistance and inductance of the bulk plasma, as well as the sheath impedance. Based on the circuit model, the electron density can be obtained according to Ohm＇s law. By using this method, the effects of the electrode shape and discharge gap on the electron density are discussed.
Based on the one-dimensional fluid model, the characteristics of homogeneous discharges with hydrogen diluted silane and argon at atmospheric pressure are numerically investigated. The primary processes of excitation and ionization and sixteen reactions of radicals with radicals in silane/hydrogen/argon discharges are considered. The effects of hydrogen dilution on the densities of species （e, H, SiH3^＋, SiH3^-, SiH3,） are analyzed. The simulation results show that the highest densities of e, Si113^＋, H, SiH3^-, SiH3 correspond to the optimal dilution concentration of H2. The deposition rate of μc-Si：H film depends on the SiH3 concentration, and atomic hydrogen in the plasma is found to play an important role in the crystallization fraction of the deposited films. This model explains the effects of H2 dilution on the deposition rate and crystallized fraction of μc-Si：H film growth.
