Ka band ∼10 MW gyro-devices: an experiment and a project

Summary form only given. The international program for development of electron-positron colliders needs high-power microwave sources at frequencies up to the millimeter-wave band. At the shortest microwaves, the highest powers are produced with fast-wave devices. Among them, the gyroklystron seems especially robust and reliable. As an introduction, a 30 GHz free running gyrotron operating at the H₅₃ mode and driven with 300 kV/80 A electron beam was manufactured and tested: 12 MW/200 ns pulses were produces with 50% efficiency. The gyrotron is planned to be converted into a gyroklystron amplifier; for better coupling to the electron beam and better suppression of parasitic modes, the modulating and intermediate cavities will operate at the H₅₁ mode. For further experiments, a test stand with a 500 kV/ 300 A/1 μs modulator is being designed and a relevant electron gun is being manufactured.