100-150 MW designs of two- and three-cavity gyroklystron amplifiers operating at the fundamental and second harmonics in X- and Ku-bands

Efficient 100-150 MW X- and Ku-band microwave sources with pulselengths of 1 /spl mu/s are being developed for driving future linear colliders. Two- and three-cavity co-axial designs of relativistic gyroklystron amplifiers are presented here which fulfill these requirements. Numerical simulations predict over 40% efficiency, 45-50 dB gain, and 100-160 MW power level for the gyroklystron designs operating at fundamental (8.568 GHz) and second harmonic (17.136 GHz). It is shown that introducing a penultimate (buncher) cavity significantly improves efficiency and gain of the second-harmonic amplifier.