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  • Open Access

Emittance preservation under multifaceted CSR effects in isochronous deflection structures for multikiloampere bunches

Xiuji Chen, Si Chen*, Duan Gu, and Haixiao Deng†

  • *Contact author: chensi@sari.ac.cn
  • †Contact author: denghx@sari.ac.cn
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Phys. Rev. Accel. Beams 29, 104903 – Published 27 October, 2026

DOI: https://doi.org/10.1103/78p2-pp2w

Abstract

In modern accelerator facilities, coherent synchrotron radiation (CSR) presents a fundamental limitation to maintaining high-brightness electron-beam quality during deflection, with accurate modeling of its effects remaining an outstanding challenge. This study introduces a novel optimization method using an integral approach to suppress CSR-induced transverse emittance degradation under two representative bunch scenarios: ultrashort bunches and high-charge long bunches. We present analytical solutions for suppressing CSR effects in the dipoles across several quadruple-bend-achromat (QBA) layouts and establish general conditions for mitigating CSR-induced emittance growth in the subsequent drift sections of isochronous beamlines. Our analysis demonstrates that the QBA is the minimal configuration capable of simultaneously suppressing transverse emittance degradation and preserving the longitudinal beam distribution. Beam tracking results show negligible emittance growth for multikiloampere bunches at a 16° deflection. Furthermore, multicell simulation confirms the exact scalability of this approach. While previous designs suffer severe emittance degradation upon cascading, the QBA maintains exceptionally preserved beam quality.

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Phys. Rev. Accel. Beams 29, 104903– Published 27 October, 2026
  • Received 17 April 2026
  • Accepted 28 September 2026
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