Extracting chromatic properties of electron beams from spectral analysis of turn-by-turn beam position data

TL;DR

This paper introduces a spectral analysis method to extract chromatic properties of electron beams directly from turn-by-turn data, enabling precise measurements of chromaticity, energy spread, and beta-beating in accelerators.

Contribution

The paper presents a novel spectral analysis technique for directly estimating chromatic parameters from beam position data, supported by analytical derivations and simulation results.

Findings

Accurately estimates linear chromaticity from spectral sidebands.

Determines RMS energy spread through frequency analysis.

Validates method with simulations and practical application at KARA.

Abstract

A method to estimate linear chromaticity, RMS energy spread, and chromatic beta-beating, directly from turn-by-turn beam position data in a circular electron accelerator, is presented. This technique is based on frequency analysis of a transversely excited beam, in the presence of finite chromaticity. Due to the turn-by-turn chromatic modulation of the beam's envelope, betatron sidebands appear around the main frequency of the Fourier spectra. By determining the amplitude of both sidebands, chromatic properties of the beam can be estimated. In this paper, analytical derivations justifying the proposed method are given, along with results from tracking simulations. To this end, results from practical applications of this technique at the KARA electron ring are demonstrated.