Resonantly Sustained Discharges by dc Current and High-Frequency Power

New results are obtained on plasma column resonances subjected to a high-frequency field for the case of high incident power. The resonance shift and hysteresis are measured with good accuracy. A theoretical model based on the energy balance of the electron gas is established. It is shown that the plasma is maintained in a resonant state by the high-frequency (HF) power with or without dc current. A graphical method to determine the electron density variation due to the HF field is described. This method predicts correctly the resonance shift and the hysteresis.