Design aspects of a 94 GHz extended interaction Klystron

Summary form only given, as follows. High power microwave generation at 94 GHz has several advantages compared to lower frequencies in radar and in communications. The resolution in radar is proportional to the wave length and there is a transmission window in air at 94 GHz. The size of the antenna scales with the wavelength and the bandwidth increases with frequency. One of the main difficulties in producing a 94 GHz klystron, running at the fundamental mode, is the manufacturing of the very small resonator. Several cavities are needed to extract the energy from the electron beam. Another difficulty arises from the small aperture available for the beam. Only a small beam loss inside the cavities can be tolerated. This requires a high-brightness beam. A combination of mechanical and chemical machining is suggested for production of the cavities. The envisioned extended interaction klystron will be excited by a 50 keV, 10 to 100 mA electron beam. The beam will be bunched by a 4-cell resonator operating in the /spl pi/-coupling and TM/sub 010/-cavity mode. The energy of the bunched beam will be extracted in a sequence of 4-cell resonators similar to the bunching resonator. It is assumed that a standing wave electric field amplitude of at least 10 MV/m on axis can be achieved. The expected microwave power is of order 1 kW.