THE USE OF HIGH-ORDER TMOMO MODES OF A RESONANT CAVITY FOR MAGNETIZED PLASMA-DENSITY MEASUREMENTS

A study of the application of high-order TM0m0 modes of a cylindrical cavity to the measurement of the density of a magnetized plasma column is presented. It is shown theoretically that judiciously chosen high-order modes have the potential advantages of both a wide operational range of densities, and a wide range for which a simple perturbation theory is valid. Furthermore, an experiment is described which shows that the TM060 mode can be excited with a sufficiently high Q value to allow accurate determination of the resonant frequencies, and hence plasma density. Favorable comparison between densities in the range 1010-10 12 cm-3 measured by means of the resonant cavity technique and microwave interferometry is presented.