A Modified Staggered Double Grating Slow Wave Structure for W-Band Dual-Beam TWT

To improve the performance of staggered double grating traveling wave tube (SDG-TWT), such as the saturated power, electron efficiency, and gain, a modified SDG (MSDG) slow wave structure (SWS) is proposed for a wide-band and high-power TWT operating in W-band or higher terahertz band. The MSDG-SWS provides not only high interactive impedance over a relatively wide frequency range but also the double beam tunnels. The physical mechanism of bandwidth broadening, interaction impedance improvement of MSDG-SWS is revealed by analyzing its electromagnetic guided wave characteristics, and the results of high-frequency characteristic indicates that, under the condition that the dispersions of the two SWSs maintain basically consistent, the passband of MSDG-SWS increases by 14 GHz over SDG-SWS, and the average interaction impedance of MSDG-SWS is larger than SDG-SWS in the frequency band below 103 GHz. Moreover, the simulation results indicate that at 17.6 kV of beam voltage and 400 mA of beam current, the MSDG-TWT can provide more than 260 W of saturated output power in the frequency range of 78–122 GHz and can reach 551 W of maximum power at 86 GHz with 7.61% of maximum electron efficiency. Thus, it can be regarded that MSDG-SWS is a promising SWS for TWTs operating in W-band or higher terahertz band.