Investigation of Sine Groove Waveguide Slow Wave Structure for Terahertz Traveling Wave Tube

A novel sine groove waveguide slow wave structure (SGW-SWS), originated from the sine waveguide (SW), is proposed for a wideband terahertz (THz) traveling wave tube (TWT). SGW-SWS not only has high interaction impedance in a relatively wide frequency band, but also has a wide beam tunnel. In addition, it can be fabricated using the Nano-Computer Numerical Control (CNC) milling techniques. The high-frequency simulation results show that, under the same dispersion, the passband of SGW-SWS is 23 GHz wider than that of SW-SWS, and the average interaction impedance of SGW-SWS is higher than that of SW-SWS in the whole passband. And the transverse dimension of beam tunnel is independent of the dispersion characteristics of SGW-SWS, so the beam current can be further increased by enlarging the size of beam tunnel. Moreover, the particle-in-cell (PIC) simulation results reveal that the saturated power and electronic efficiency of SGW-TWT in the frequency range of 201-260 GHz are more than 84.9 W and 2.72%, respectively, when the operating voltage is 20.8 kV and the beam current is 150 mA.

Automated summary

The novel sine groove waveguide slow wave structure (SGW-SWS) proposed for wideband terahertz (THz) traveling wave tube (TWT) shows high interaction impedance, wide beam tunnel, and can be fabricated using Nano-Computer Numerical Control (CNC) milling techniques. Compared to the sine waveguide slow wave structure (SW-SWS), SGW-SWS has a wider passband and higher average interaction impedance throughout the passband. The beam tunnel size of SGW-SWS is independent of dispersion characteristics, allowing for further increase in beam current.