Power and mode diagnostics for high‐power microwave sources with over‐moded output (abstract)

摘要

A microwave calorimeter has been developed in the course of our work on virtual‐cathode‐oscillator microwave generators which may have application to gyrotrons used for plasma heating. The absorbing element uses a novel conductor array which provides a means of temperature‐rise detection. Provision has been made to observe the spatial pattern of the microwave energy deposition with an infrared imaging system. The infrared image provides output mode information and a noncontacting measure of the total energy in the microwave pulse. The microwave absorption of the calorimeter has been evaluated from 8 to 40 GHz with broadband TM01 mode launchers. Mode selective directional couplers are also being developed to provide an independent measure of the mode number for the transverse magnetic (TM0n) modes which are generated by the virtual‐cathode oscillator. This technique can also be utilized to discriminate other higher‐order modes.1 This work was supported by the U. S. Department of Energy.