HIGH-POWER OPERATION OF A K-BAND 2ND-HARMONIC GYROKLYSTRON

Amplification studies of a two-cavity second-harmonic gyroklystron are reported. A magnetron injection gun produces a 440 kV, 200-245 A, 1 m us beam with an average perpendicular-to-parallel velocity ratio sligh tly less than 1. The TE011 input cavity is driven near 9.88 GHz and th e TE021 output cavity resonates near 19.76 GHz. Peak powers exceeding 21 MW are achieved with an efficiency near 21% and a large signal gain above 25 dB. This performance represents the current state of the art for gyroklystrons in terms of the peak power normalized to the output wavelength squared.