Experimental Study on Generation of a Higher Order Mode for W-band Gyrotron Oscillator

Abstract

This thesis reports the design and experimental demonstration of a mode generator for a TE_62 mode, operating at 95 GHz. The excitation of a target mode for a cold test has been performed in the mode generator. The cavity mode of a mode generator excites the TE_62 mode by means of a fundamental mode. A TE_62 mode was chosen as a cavity mode for a W-band Gyrotron. In order to test the performance, the TE_62 mode generator has been developed for a cold test. Quasi-optical analysis has been done for designing mode generator. A Gaussian-like beam from a corrugated feed horn using a vector network analyzer propagates to the cavity which was made translucent by array of holes. The measurement is very sensitive to the experimental conditions such as coupling of the cavity, alignment, and undesirable interception from the reflected beam. Simulations were done by High Frequency Structure Simulator (HFSS) and CST MICROWAVE STUDIO (CST MWS), and then compared to the experimental results.