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Studies of enhanced SASE at the soft x-ray beamline Athos at SwissFEL

S. Reiche* and E. Prat

A. Dax, M. Huppert, S. Neppl, A. Trisorio, and C. Vicario

E. Ferrari

  • *Contact author: sven.reiche@psi.ch
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Phys. Rev. Accel. Beams 29, 083403 – Published 24 August, 2026

DOI: https://doi.org/10.1103/qw1g-ffds

Abstract

We present studies on enhanced SASE at the soft x-ray beamline Athos at SwissFEL. The generation of a series of current spikes with 790 nm spacing is injected into the Athos undulator beamline. Due to strong space-charge forces, the optimum performance occurs with a strong positive taper of the undulator field. There is a clear modal structure in the observed spectra, indicating the presence of a train of attosecond FEL pulses with no intrinsic phase-locking. The space-charge dynamics causes an elongation of the current spike and a redshift in the bunching spectra, which determines the optimum taper gradient.

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Phys. Rev. Accel. Beams 29, 083403– Published 24 August, 2026
  • Received 3 February 2026
  • Accepted 24 July 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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