Research on 0.22THz folded-waveguide traveling-wave tube with a proper phase-velocity taper

This paper presents a 0.22THz big beam-tunnel folded-waveguide (FWG) traveling-wave tube (TWT) with a phase-velocity taper. The big beam tunnel was applied in order to reduce the processing difficulty and increase the capability of the direct current power. And the input and output coupling structures and attenuator were simulated and the entire tube transmission characteristic was analyzed by employing high-frequency simulation software (HFSS). Moreover, the phase velocity taper was put into use for the purpose of both being easy to be fabricated in engineering and improving the electron efficiency in the whole operating frequency ranges. From the beam-wave interaction simulated by using beam-wave interaction simulation method, the output power and electron efficiency at center frequency could be significantly promoted from 79W and 3.49% to 103W and 4.54% respectively after using the taper at the rear half of the tube.