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Mitigation of transverse single-bunch instabilities with longitudinal impedance, feedback, and chromaticity

Liwei Pan1,2, Yuan Zhang1,2,*, Kazuhito Ohmi1,3, Chuntao Lin1, Na Wang1, Yuzhe Liu1,2, and Siyuan Feng1,2

  • *Contact author: zhangy@ihep.ac.cn
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Phys. Rev. Accel. Beams 29, 051001 – Published 15 May, 2026

DOI: https://doi.org/10.1103/1kpk-757b

Abstract

In this paper, we investigate methods for suppressing transverse single-bunch instability. A theoretical framework incorporating longitudinal impedance, feedback, and chromaticity is presented. Our results show that the combined action of these effects effectively suppresses the transverse single-bunch instability. The instability threshold can be raised by a factor of 2 or more relative to Itmci, defined as the threshold under transverse impedance only. The key stabilization mechanism arises from two effects: feedback and positive chromaticity cause the instability to be dominated by nonzero-order azimuthal modes, while longitudinal impedance introduces a significant tune spread in these modes. This stabilization mechanism, however, is ineffective in the negative chromaticity regime. The theory is applied to three electron storage rings: SuperKEKB, CEPC, and HEPS. Both the analysis and simulation lead to consistent conclusions.

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Phys. Rev. Accel. Beams 29, 051001– Published 15 May, 2026
  • Received 10 January 2026
  • Accepted 15 April 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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