Suppressing Coherent Synchrotron Radiation Effects in Chicane Bunch Compressors

TL;DR

This paper analyzes and proposes asymmetric chicane designs to effectively suppress coherent synchrotron radiation effects, thereby preserving beam quality during high-current bunch compression in accelerator light sources.

Contribution

It introduces a novel analysis of CSR cancellation conditions and demonstrates asymmetric chicane schemes that significantly reduce emittance growth.

Findings

Asymmetric chicanes can cancel CSR effects more effectively.

Proposed schemes drastically suppress emittance growth.

Verification through simulations confirms the effectiveness.

Abstract

The most significant advances in the accelerator-based light sources (i.e., x-ray free electron lasers) are driven by the production of the high final peak current in the last several decades. As a prerequisite to attain the proposed high brightness, the symmetric C-chicane bunch compressor is typically exploited due to its simplicity, efficiency, and natural dispersion-free feature at all orders. However, during bunch compression for a high peak current requirement, a main contributing factor to the transverse emittance degradation is the emission of the coherent synchrotron radiation (CSR). Suppressing this effect is necessary to preserve the beam phase-space quality. To this end, this paper presents an analysis of one-dimensional CSR point-kick and derives the cancellation conditions in terms of compression factor. The CSR cancelation conditions indicate an asymmetric geometric design. We demonstrate concrete schemes for asymmetric C- and S-chicanes, and verify the CSR cancelation conditions using integration methods and ELEGANT simulations. Furthermore, the proposed asymmetric C- and S-chicanes can drastically suppress the emittance growth compared with the symmetric ones with identical bunch compression goals.