Design of new concept cavity for high power gyroklystron

Summary form only given. In the development of high power and high efficiency gyroklystron, mode purity in the input cavity is one of the important factors that affects the interaction of input RF signal and electron beam. In order to obtain a pure mode input structure for our gyroklystron, a coaxial dual-cavity with an outer TE/sub 411/ and inner TE/sub 011/ coaxial cavities has been designed to get a low Q and to avoid mode distortion due to the coupling apertures between the input waveguide and input cavity. Furthermore, in order to inject the output power of the gyroklystron into our future pulse compression system, a coaxial TE/sub 021/ cavity with a TE/sub 02/-TE/sub 01/ mode converter is proposed and designed as the output structure of our advanced design gyroklystrons. The output power can be extracted radially, and at the same time the TE/sub 02/ mode is converted to TE/sub 01/ mode into a circular waveguide. The preliminary experimental results of the dual-cavity input structure showed that a reasonably low quality factor with high mode purity at the design frequency had been realized by this dual-cavity structure, and, the experimental results are in good agreement with the theoretical design. The details of the dual-cavity TE/sub 011/ input structure and TE/sub 02/-TE/sub 01/ mode converter output structure will be presented.