Design of a Phase-Velocity Taper Traveling Wave Tube Based on Double-Corrugated Waveguide Slow Wave Structure With Grating

This article presents a double-corrugated waveguide with grating (DCWG) slow wave structure (SWS) designed for traveling wave tube (TWT) applications and integrates it into the development of a two-section TWT. The DCWG structure exhibits a high and relatively uniform interaction impedance, which enhances interaction efficiency. Moreover, the phase velocity demonstrates minimal sensitivity to variations in slot size within the DCWG, effectively mitigating the challenges associated with phase velocity control in the terahertz frequency range. This characteristic makes the application of phase velocity tapering technology in G-band TWTs both practical and viable. Simulation results, conducted at an electron beam voltage of 11.8 kV and a beam current of 0.1 A, indicate that the saturated output power of the uniform DCWG TWT reaches a maximum of 48 W, with a 3 dB bandwidth exceeding 16%. Upon introducing a phase velocity gradient, the saturated output power further increases to 66 W, the maximum gain improves by approximately 1.4 dB, while maintaining a 3 dB bandwidth greater than 10%.