Development of a 50 MW 30 GHz Gyroklystron Amplifier

DOE requires sources for testing of high gradient accelerator structures. A power of 50 MW is required at K and Ka band. The pulse length must be ~ 1 microsecond and the pulse repetition frequency at least 100 Hz. At least some applications may require phase stability not offered by a free running oscillator. CCR proposed to build a 50 MW 30 GHz gyrklystron amplifier. This approach would give the required phase stability. The frequency was at the second harmonic of the cycltron frequency and used the TE02 mode. This makes it possible to design a device without an inner conductor, and with a conventional (non-inverted) MIG. This minimizes cost and the risk due to mechanical alignment issues. A detailed design of the gyroklystron was produced. The design was based on simulations of the cavity(ies), electron gun, output coupler and output window. Two designs were produced. One was at the fundamental of the cyclotron frequency. Simulations predicted an output power of 72 MW with an efficiency of 48%. The other was at the second harmonic, producing 37 MW with an efficiency of 37%