Design of a 10-MW, 91.4-GHz frequency-doubling gyroklystron for advanced accelerator applications

A 10-MW, 91.4-GHz gyroklystron is under development for W-Band accelerator applications. The device is expected to generate 1-mus pulses at up to 120 Hz, with efficiencies near 38%, with a gain above 57 dB, A double-anode, ma gnetron injection gun operating at 500 kV will provide a 55-Ampere beam for interaction with a six-cavity circuit in a magnetic field of about 27.9 kG . The beam will have an average perpendicular-to-parallel velocity ratio of approximately 1.6 with a parallel velocity spread below 3.3%. The first tw o cavities will operate in the TE011 mode at the drive frequency near 45.7 GHz, while the remaining cavities will operate in the TE021 mode at twice t he drive frequency. The output cavity will have smooth radial wall transiti ons to minimize mode conversion and pulse heating, the latter of which is s hown via thermal modeling to be within acceptable limits, The output signal will be in a TE01/TE02 mode mixture for easier power handling and to facil itate possible depressed collector operation, which could result in wall pl ug efficiencies in excess of 50%. A complete description of the system desi gn and modeling is presented.