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High-harmonic coherent pulse generation in a storage ring using multiple-echo-enabled harmonic generation

Weihang Liu1,2, Yu Zhao1,2, Weilun Qin1,2, Yi Jiao1,*, Xiao Li1,2,†, and Sheng Wang1,2,‡

  • *Contact author: jiaoyi@ihep.ac.cn
  • †Contact author: lixiao@ihep.ac.cn
  • ‡Contact author: wangs@ihep.ac.cn
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Phys. Rev. Accel. Beams 29, 093405 – Published 25 September, 2026

DOI: https://doi.org/10.1103/6gc2-41zw

Abstract

Fourth-generation storage-ring light sources have achieved transverse emittances approaching the diffraction limit at x-ray wavelengths, while their longitudinal coherence remains limited. Existing laser-modulation schemes can induce strong microbunching, but most storage-ring implementations produce only one useful coherent output from a given longitudinal region during each revolution, thereby underutilizing the intrinsic multiuser capability of storage rings. We propose a multiple-echo-enabled harmonic generation (multi-EEHG) scheme that applies successive excitation-echo cycles to the same longitudinal slice of a stored bunch within one revolution, enabling coherent-radiation delivery to multiple beamlines at different wavelengths. A general formulation of the n-stage EEHG bunching factor and a corresponding optimization procedure are derived. As an example, a triple-EEHG configuration is designed for the southern advanced photon source storage ring. Simulations demonstrate coherent radiation at multiple wavelengths with single-pulse photon numbers up to 109, corresponding to an enhancement of approximately three orders of magnitude over synchrotron radiation for the same spectral bandwidth, while achieving few-meV bandwidth without a monochromator. The proposed scheme offers a scalable approach for multibeamline coherent operation in next-generation storage-ring light sources.

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Phys. Rev. Accel. Beams 29, 093405– Published 25 September, 2026
  • Received 6 March 2026
  • Accepted 4 September 2026
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