A Wideband High-Phase Flatted-Grating Folded Waveguide TWT With an Electron Optical System and Brewster Windows

In this article, a network consisting of a high-phase (HP) flatted-grating folded waveguide (FGFW), an electron optical system (EOS), and a Brewster vacuum window has been developed for a wideband 0.6 terahertz (THz) traveling-wave tube (TWT). The HP-FGFW slow wave structure (SWS) provides large dimensions, facilitating fabrication, significant weak dispersion characteristic, low ohmic loss, and satisfactory amplification performance. The EOS is based on a double-anode electron gun and a permanent uniform magnetic field focusing system. This system can generate a 15-mA, 19.0-kV circular beam and stably transmit 40 mm without being intercepted in a tunnel with a radius of 50 μm. To match the wideband feature of the HP-FGFW TWT, a Brewster window was designed, analyzed, fabricated, and tested with transmission characteristics covering 500–750 GHz. Overall, this collaborative combination scheme not only provides a promising solution for wideband 0.6-THz TWTs but also establishes a foundation for the practical implementation of applications in THz communication and imaging systems.