An Improved Slow-Wave Structure for the Sheet-Beam Traveling-Wave Tube

摘要

Based on the previous double-staggered grating waveguide slow-wave structures (SWSs), an improved design is presented in this paper. The linear profile of the beam tunnel is replaced by a curved shape on its broad side. The high-frequency characteristics and beam–wave interaction are presented before and after the alteration. A novel approach in loading the attenuator with high attenuation is proposed to ensure a stable beam–wave interaction for the improved SWS. From our calculations, the improved SWS possesses a larger average interaction impedance with a rate of about 13.1%. Particle-in-cell simulation predicts that the saturated output power, the corresponding gain, and the electronic efficiency are all significantly improved, with an increase of more than 1-kW output power and 3-dB gain over the operating frequency range, and the maximum efficiency increases from 19.4% to 22.2%. The operating bandwidth is almost unaffected, remaining in a frequency range from 38 to 46 GHz.