Mechanisms of Resonant Power Input into a Magnetoactive RF Discharge Plasma

Abstract

We consider the excitation and absorption of waves in a magnetoactive rf discharge plasma in the conditions when the generator frequency is lower than the electron cyclotron frequency. We consider the cases of unconfined and confined plasmas in the cylindrical geometry and different regimes of excitation of plasma waves with different dispersion relations and field polarizations. The power input to the plasma depends on the distribution of external-source currents initiating the discharge and on the density parameter characterizing the plasma density and transverse sizes of the system. In the case of a plasma cylinder with a free surface or a plasma cylinder in a large conducting casing, which is most interesting for applications, plasma contains only potential and nonpotential E-type oblique Langmuir waves as well as a strongly nonpotential surface wave. The latter wave is practically not excited by external currents flowing over the cylinder surface for real parameters of the system. For high values of the density parameter, the effective resistance of the plasma with inducting excitation of the discharge is predominant. For moderate and low values of this parameter, capacitive excitation of the wave by the current on the plasma cylinder surface is found to be most effective.