Design considerations for a 100 kW CW, 140 GHz gyrotron oscillator

A gyrotron oscillator capable of generating 100 kW of CW power is currently under development at Varian. The tube is being designed for operation in the TE
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^o
cavity mode with the electron beam located at the second radial electric field maximum in the cavity. The electron beam will be produced by a magnetron injection gun and the 56 kG magnetic field required for 140 GHz operation will be provided by a superconducting magnet. Initial design calculations for the important elements of the tube are reported and the various technology issues of the tube design are discussed.