Cusp gun TE/sub 21/ second-harmonic gyro-TWT amplifier

A second harmonic cusp-gun TE/sub 21/ gyro-TWT amplifier is being constructed at UCD that is predicted to generate 50 kW at 30 GHz with 20% efficiency, 30 dB saturated gain and 3% bandwidth. The device is to be driven by a 70 kV, 3.5 A axis-encircling electron beam from a Northrop Grumman cusp gun. The device takes advantage of the concept that harmonic gyro-TWT's are more stable and can produce higher power than at the fundamental-harmonic, because their weaker interaction yields a higher threshold electron current for the absolute instability at the cutoff of the operating mode.