On Electron-Cyclotron Wave Resonance in Inductively Coupled hf Discharges

The theory of Pfeiffer on electron-cyclotron wave resonance phenomenon in inductively coupled hf ring discharges has been extended by Sager to include electron temperature, nonuniform density distributions, and the finite dimensions of a plasma of rectangular cross section. A scheme is herein proposed for adapting Sager's results to the experimentally important case of circular cross section. In order to test the scheme, an experiment was conducted in a low-pressure hf (27 MHz) argon discharge of cylindrical geometry with plasma densities in the range (1.0–3.5)×1011/cm3 and static magnetic fields less than 60 G. The agreement between theory and experiment is found to be good and lends credence to the scheme as a means for predicting resonance values of the magnetic field in cylindrical hf discharges.