5 KW Pulse/2 KW CW high efficiency S-band dual mode traveling-wave tube

Techniques resulting in high efficiency over extended bandwidths have been investigated. The objective was to obtain both a high average power capability and high efficiency at differing output power levels. A dual mode electron gun has been designed and evaluated. Favorable beam characteristics have been demonstrated at different perveance levels corresponding to both modes of operation, Suitable dispersion shaping methods have resulted in high interaction impedances with small phase velocity variations over octave bandwidths. Large signal computer evaluations considering beam-circuit wave velocity resynchronization techniques have been conducted. The tube employs a multi-stage depressed collector to further improve efficiency. Output power levels of 5kW have been demonstrated at 10% duty in the high mode and continuous wave power levels of 2kW have been attained in the low mode. Minimum octave bandwidth pulse efficiencies of 38% and continuous wave efficiencies of 45% have been demonstrated. The performance of this device represents a significant advance in the state of the art of high efficiency dual mode. TWT´s.