Performance characteristics of a high-power X-band two-cavity gyroklystron

The operating characteristics of a two-cavity X-band gyroklystron experiment are reported. Beam voltages and currents up to 440 kV and 200 A, respectively, are generated in 1 is pulses by a thermionic magnetron injection gun. Velocity ratios [mathematical expression omitted] near one in the output cavity are used to achieve peak powers of 24 MW near 9.87 Ghz. The maximum saturated efficiency of more than 33% occurs at a beam voltage of 425 kV and a current of 150 A. A large signal gain in excess of 34 dB is realized by operating the input cavity just below the start oscillation threshold. Details of tube stability and the dependence of amplification on magnetic field profile, input signal parameters, and various beam quantities are presented.