Cylindrical Microwave Cavity Research Articles

Resonances of a Microwave Cavity Partially Filled with a Plasma

The resonant behavior of a cylindrical microwave cavity partially filled with a cold plasma of arbitrarily large density is studied theoretically and experimentally. Curves showing the resonant frequencies as functions of the plasma density are given for the lower order modes. The modes are generally not pure TE or TM modes but are of hybrid character. In addition to the modes that are related to those of the empty cavity, there is a class of modes of surface wave character that do not exist in the empty cavity. Experiments have been performed and are generally in agreement with the theory. However, for some modes great discrepancies are observed. These correspond to the unexplained additional resonances obtained in plasma resonance experiments.

A PROPOSAL TO USE MICROWAVE CAVITIES TO STUDY THE SURFACE PROPERTIES OF HIGH DENSITY PLASMAS

It is suggested that the resonant properties of a cylindrical microwave cavity containing a highly conducting axial plasma rod could be used to obtain information about the dynamic properties of such a plasma. Two applications of the method are considered: an investigation of electrically exploded wires, and a study of the dynamics of the conventional z-pinch during its initial stages.

Microwave Breakdown of a Gas in a Cylindrical Cavity of Arbitrary Length

It is possible to consider breakdown in a cylindrical microwave cavity whose radius is large compared to its length as approaching the conditions of parallel plate breakdown. This assumption has been used to measure high frequency ionization coefficients. The present paper investigates the corrections to be made when the length is increased. Numerical results are given for cavities whose ratios of radius to length are as low as 0.5, and the method is applicable to any cylindrical cavity. The breakdown data in these longer cavities are used to extend the high frequency ionization coefficient curves for air by a factor of ten.