Operation of a thermionic gyro-TWT with a helical interaction waveguide

Summary form only given. Gyrotron travelling wave tube (gyro-TWT) experiments, based on a helically corrugated waveguide, have been undertaken at Strathclyde University for the last few years. The helically corrugated gyro-TWT amplifier is capable of providing broadband amplification with superior efficiency to smoothbore gyro-TWAs due to the favourable dispersion of the helically corrugated interaction region. The corrugation radically changes the wave dispersion such that the eigenwave has an almost constant value of group velocity over a wide frequency band in the region of small axial wavenumbers, thereby increasing the band of the resonant electron-wave interaction. Our earlier experiments employed a cold cathode to generate the electron beam and therefore used short pulses (100 ns). The latest experiments, reported here, employ thermionic cathodes, therefore allowing the use of a longer pulse electron beam (1 μs).