Cherenkov loss factor of short relativistic bunches:general approach

TL;DR

This paper introduces a general integral approach to calculate Cherenkov loss factors for short relativistic bunches in various waveguides, unifying previous models and enabling analysis of complex systems.

Contribution

A new general integral method for calculating Cherenkov loss factors in arbitrary waveguides with short relativistic bunches.

Findings

Method matches conventional results for known waveguides

Applicable to waveguides with arbitrary slowdown layer thickness

Simplifies analysis of complex accelerator components

Abstract

The interaction of short relativistic charged particle bunches with waveguides and other accelerator system components is a critical issue for the development of X-ray FELs (free electron lasers) and linear collider projects. Wakefield Cherenkov losses of short bunches have been studied previously for resistive wall, disk-loaded, corrugated and dielectric loaded waveguides. It was noted in various publications [1] that if the slowdown layer is thin, the Cherenkov loss factor of a short bunch does not depend on the guiding system material and is a constant for any given transverse cross section dimensions of the waveguides. In this paper, we consider a new approach to the analysis of loss factors for relativistic short bunches and formulate a general integral relation that allows calculation of the loss factor for a short relativistic bunch passing an arbitrary waveguide system. The loss factors calculated by this new method for various types of waveguides with arbitrary thickness slowdown layers, including infinite media, are shown to be equivalent to those obtained by a conventional approach.