INTERMEDIATE-PRESSURE ELECTRODELESS DISCHARGES IN RF AND PULSED FIELDS.

Steady-state capacitive electrodeless discharges are investigated for pressures of tens of torr and above. The discharges are sustained by rf fields and periodic high-voltage pulses. The voltage-current characteristics are calculated. Particular attention is paid to the space-charge sheaths which form near the plasma boundaries. The thicknesses of the sheaths and the voltage drops across them are estimated in an effort to determine how the sheaths affect the discharge. The question of a constant potential of the rf plasma is discussed. A model is presented for a periodic-pulse discharge in which substantial sheaths similar to the discharge gap with a high overvoltage should appear.