Helical Groove Loaded Staggered Double Grating Slow-Wave Structure for W-Band Traveling Wave Tubes

A novel all-metal slow-wave structure (SWS), named the helical groove loaded staggered double grating (HGL-SDG), is studied in this article. By loading the conventional helical groove waveguide (HGW), reconfiguration and optimization of the transverse layout of the staggered double grating (SDG) are achieved. Numerical eigenmode analyses reveal that, compared to the conventional HGW (C-HGW), the HGL-SDG demonstrates weaker dispersion and a higher interaction impedance. Compared to the SDG, the HGL-SDG exhibits improved dispersion characteristics, lower group velocity, comparable ohmic losses, and an enhanced interaction impedance. Furthermore, beam–wave interaction simulations of HGL-SDG traveling wave tubes (TWTs) predict the improvements in saturated output power and efficiency across the 88–102-GHz frequency range compared to conventional SDG-based TWTs. The HGL-SDG is expected to enhance the amplification performance of SDG-TWTs and can be fabricated using state-of-the-art 3-D-printing technologies, enabling practical implementation of these advancements.