Interaction between a Dielectric (or Cold Plasma) and a Cavity

Abstract

This paper treats the interaction between a cylindrical plasma column (or dielectric material) and a resonant cavity from which it protrudes. From the results, one may determine the dielectric constant and loss, or in the case of a plasma, the plasma frequency and collision frequency, given measured values of the resonant frequency shift and change in the cavity Q. This theory differs from earlier theory on cylindrical cavities in that it treats a cavity of more general shape, although restricted to TM modes, and takes into account the subtle boundary effects at the openings through which the plasma is admitted. These effects may be calculated by estimating the field variation over the part of the cylindrical plasma surface that lies inside the cavity.