Design and operation of a four-cavity gyroklystron circuit

Summary form only given, as follows. At the University of Maryland, we have been exploring the possibility of using gyroklystrons to drive advanced linear colliders in X- and Ku-bands. Recently, we produced over 75 MW of peak power at 8.57 GHz with a 3 cavity first harmonic coaxial system. Based on these results, we have designed a high-gain 4 cavity frequency-doubling system and an output waveguide system which transforms the power from the output cavity (in the TE/sub 021/ mode) and equally divides it into two standard WR62 rectangular waveguides. We expect to use this latest system to energize and test Ku-Band accelerator structures. In this paper we will present the experimental results of our 4 cavity, frequency-doubling coaxial gyroklystron, which we expect to produce over 80 MW of peak power at 17.14 GHz in 1 microsecond pulses. The beam voltage and current are 460 kV and 540 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 at our design point are about 35% and 60 dB, respectively. This tube is driven by a TWT, and efforts to measure and minimize phase jitter will be described. Preliminary experimental results will be given for the traditional output waveguide mode (TE/sub 02/). Finally, we will discuss our designs of output waveguide/mode converter system. We will compare the theoretical calculations with the cold test results for each of the components used in the system and will present the amplitude and phase balance measurements for the two output rectangular waveguides.