35 GHz gyroklystron amplifiers

Summary form only given. Experiments on two-cavity and three-cavity gyroklystron amplifiers are underway to demonstrate a 140 kW, 35 GHz coherent radiation amplification for radar applications. High power, high duty (10%) relevant gyroklystrons require a TE/sub 011/ cylindrical cavity mode, operating at a fundamental beam cyclotron mode. An electron beam of 70 kV, 6 A produced from a magnetron-injection-gun is injected into the cavities through a high compression magnetic field powered by a 13 kG superconducting magnet. Drift tubes consisting of lossy ceramic rings are designed to suppress undesired oscillations. A drive signal is injected into the first cavity through a mode selective coaxial coupler. A capacitive probe is placed directly before the input cavity to measure the beam velocity ratio. Large signal non-linear calculations predict that the two-cavity gyroklystron will produce a peak power of 140 kW, corresponding to efficiency of 33% and a saturated gain of 23 dB over a 0.35% bandwidth at /spl alpha/=1.5, /spl Delta/v/sub z//v/sub z/=15%, 13.3 kG, Q/sub 1/=150, and Q/sub 2/=200. In order to increase an amplifier bandwidth, a stagger tuned three cavity circuit is designed.