Using pipe with corrugated walls for a sub-terahertz FEL

TL;DR

This paper explores the excitation of a resonant high-frequency mode in a corrugated metallic pipe using free electron laser instability, potentially enabling sub-terahertz FEL operation.

Contribution

It introduces a novel method of exciting resonant modes in corrugated pipes via FEL instability, expanding the understanding of high-frequency beam-wave interactions.

Findings

Resonant mode can be excited by FEL instability in corrugated pipes.

The mechanism works with bunch lengths much longer than the radiation wavelength.

Potential for sub-terahertz FEL development.

Abstract

It has been noted in the past, in the study of the wall-roughness impedance, that a metallic pipe with corrugated walls supports propagation of a high-frequency mode that is in resonance with a relativistic beam. This mode can be excited by a beam whose length is a fraction of the wavelength. In this paper, we study another option of excitation of the resonant mode in a metallic pipe with corrugated walls---via the mechanism of the free electron laser instability. This mechanism works if the bunch length is much longer than the wavelength of the radiation.