Design and operation of harmonic coaxial gyroklystrons for accelerators

The authors present the experimental results of a 3 cavity, second harmonic coaxial gyroklystron tube, which is expected to produce over 80 MW of peak power at 17.14 GHz in I /spl mu/s pulses. The beam voltage and current are 500 kV and 480 A, respectively, and the applied magnetic field is about 5 kG. The input cavity operates near the cyclotron frequency at 8.57 GHz; all other cavities operate near the second harmonic at 17.14 GHz. The expected interaction efficiency and gain are 33% and 49 dB, respectively. The theoretical dependence of efficiency on drive power and the average velocity ratio of the beam is given.