# Double-Staggered Grating Waveguide Slow Wave Structure for Terahertz Traveling Wave Tube

## TL;DR

This paper introduces a new waveguide structure for terahertz TWTs that efficiently amplifies signals with high gain and low reflection.

## Contribution

The novel double-staggered grating waveguide design enables wideband operation and improved performance in terahertz TWTs.

## Key findings

- The DSGW–SWS achieves a reflection coefficient below −15 dB from 326 GHz to 364 GHz.
- A 340 GHz signal is amplified from 0.19 W to 17.4 W with a gain of 19.55 dB in PIC simulations.

## Abstract

A double-staggered grating waveguide slow wave structure (DSGW–SWS) is designed for a 340 GHz traveling wave tube (TWT). Input and output couplers were also designed to isolate the electron beam source from the electromagnetic (EM) signal. Transition sections in the SWS circuits were made by tapering the height of the DSWG to improve the matching of the circuit with the couplers. The reflection coefficient has a wide range from 326 GHz to 364 GHz below −15 dB. Particle-in-cell (PIC) simulation is performed using an ideal particle source for sheet electron beam (SEB), considering the filling factor to be around 50%. The average input power of a 340 GHz signal is said to be 0.19 W, which is amplified to 17.4 W with a gain of 19.55 dB.