An experimental gyro-TWT

Three experimental gyro traveling wave tubes (TWTs) have been built and tested. All tubes used a fundamental cyclotron resonance interaction with the circularly polarized TE(11)0 dominant waveguide mode. The tubes differed in the length of the single circuit section and in the amount of distributed loss used. The experiments were conducted at 5 GHz, with the object of producing a design that could be scaled to 94 GHz. Results on the third experiment include measurements of stable gain as high as 24 dB small signal and 18 dB saturated. A saturated power output of 120 kW at a total beam efficiency of 26% was measured with a 3-dB saturated power output bandwidth of 6%.