The harmonic gyroklystron' (HGK) is capable of generating kilowatts of average power at millimeter wavelengths. Operatingthe device at a harmonic (n > 1) of the cyclotron frequency reduces the required magnetic field to levels attainable by normalsolenoids. Size and weight of the device are reduced with a normal solenoid. An advanced centerpost (ACP) gun is usedto generate the hollow axis-encircling beam. Computer simulations predict very low velocity and guiding center spreads inthe beam. A 95 GHz fourth harmonic HGK design simulation predicts 30% overall efficiency and > 2kW average power.The electron gun will be tested in a beamstick in which the rf circuit is replaced by segmented capacitive probes.
G. P. Scheitrum,
"95 GHz harmonic gyroklystron", Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 21047C (30 November 2017); doi: 10.1117/12.2298696; https://doi.org/10.1117/12.2298696