Study of Performance Improvement for a Q-Band Sheet-Beam Traveling-Wave Tube

The study of performance improvement for a Q-band sheet-beam traveling-wave tube (SB-TWT) based on an improved double-staggered grating waveguide slow-wave structure (SWS) is presented. To enhance the tube performance, such as reducing the driving power requirement and increasing the electronic efficiency, three approaches were combined together in the tube design, including making the operating frequency be closer to the cutoff frequency of the SWS, improving the SWS with a curved beam tunnel, and introducing the phase velocity tapering technique. Beam-wave interaction simulations predicted that great improvements have been achieved. The output power, gain, and electronic efficiency at 42.5 GHz have, respectively, increased from 7.5 to 20.2 kW, from 23.7 to 60 dB, and from 13.9% to 30.3%, in comparison with a previously designed SB-TWT.