Design and operation of a 70 GHz second harmonic four cavity gyroklystron for radar applications

Summary form only given. In this paper, we present the application of this frequency-doubling technology to an existing first harmonic gyroklystron which has been under investigation at the Naval Research Laboratory. This system has been successfully operated with from 2-5 cavities. In a two cavity system, a peak power of 210 kW was achieved near 35 GHz with 37% efficiency and a gain near 24 dB. The bandwidth was approximately 0.36%. The nominal beam parameters include a voltage of 70 kV, a current of 8 A, and a perpendicular to parallel velocity ratio of about 1.35. In our experiment, we utilize the first harmonic input and gain cavities, but replace the penultimate and output cavities with ones that are designed to operate in the TE/sub 021/ mode near 70 GHz. About 140 kW of power with an efficiency near 25% is predicted via MAGYKL simulations. The complete design simulations and cold test results for this system will be presented. If viable, the experimental hot test results will also be described.