Simulation analysis of rectangular dielectric-loaded traveling wave amplifiers for THz-sources

TL;DR

This paper presents non-linear simulation results for a 220-GHz dielectric-loaded traveling wave amplifier, validating linear theory, analyzing beam-wave interactions, and proposing a symmetric RF coupler scheme.

Contribution

It introduces a comprehensive simulation analysis of a THz dielectric-loaded TWA, validating theoretical models and proposing a new RF coupler configuration.

Findings

RF power gains agree with Pierce three-wave theory and particle simulations.

Initial beam-wave interaction shows positive RF power gain.

Proposed symmetric RF coupler scheme improves performance.

Abstract

Non-linear simulation results for a 220-GHz rectangular dielectric-loaded traveling wave amplifier are presented. Simulations are used to check a linear theory that is developed by phenomenological introduction of an effective dielectric parameter for electron beam channel, and it is found that the RF power gains from Pierce three-wave theory and particle simulations are in reasonable agreement. It is shown that the RF power gain during initial beam-wave interaction is positive; the falling on the initial RF power profile, which has been thought to be the RF power transferred to the beam for bunching buildup (negative gain effect), is probably resulting from numerical errors. Beam-wave interaction mechanism is analyzed by examining the evolution of beam bunching centers. Influences of various parameters on amplifier performance are examined, and transverse space-charge effect is analyzed. A symmetric excitation scheme for RF couplers is proposed, and RF field jumps on the common intersection line of vacuum, dielectric, and metal wall, which is found in RF simulations, are explained theoretically.