On the Impedance of the High-Frequency Capacitive Discharge at Different Excitation Methods

Abstract A low-pressure (ν ≪ ω) capacitive high-frequency discharge with large-area electrodes when it is excited by an electromagnetic field with a frequency from 13 to 900 MHz is considered. General analytical formulas are obtained for the amplitudes of natural waves and the impedance of the discharge. It is taken into account that the excitation of surface waves and higher nonpropagating modes occurs due to the axial inhomogeneity of the plasma–metal layer structure and due to edge effects at the electrode cut. The higher amplitude of the resonance modes in this case (in comparison with the excitation of the discharge by a TEM wave) leads to a greater irregularity in the dependence of the discharge impedance on the electron density. This conclusion is confirmed by the direct calculation of impedance using the Comsol Multiphysics® software.