Alpha and gamma RF capacitance discharges in N2at intermediate pressures

Measurements have been made on the current and voltage characteristics and the time-resolved and time-averaged visible emission of alpha-( alpha -) and gamma- ( gamma -) type RF capacitative discharges in N 2 at frequencies between 10 and 60 MHz over the pressure range 10 to 100 Torr. A time-dependent model is proposed for alpha -type discharges that yields electron energy and density, internal potentials, discharge current and power dissipation given the measured parameters of inter-electrode voltage and separation, gas pressure and RF frequency. The model predicts considerable energy dissipation in the near electrode sheaths and elucidates the increasing stability of alpha discharges for higher input powers as the RF frequency is raised.