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Formation of nanosecond multibunch structure in thermionic electron beams and generation of multibunch x-ray free-electron laser pulses

Kazuaki Togawa*, Hirokazu Maesaka, and Vitaliy Goryashko†

  • *Contact author: togawa@spring8.or.jp
  • †Present address: FREIA Laboratory, Department of Physics and Astronomy, Uppsala University, Ångströmlaboratoriet, 75120 Uppsala, Sweden.
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Phys. Rev. Accel. Beams 29, 093401 – Published 9 September, 2026

DOI: https://doi.org/10.1103/3x73-lc4f

Abstract

The x-ray free-electron laser (XFEL) facility SACLA uses a thermionic pulsed electron gun and a beam chopper to produce a low-emittance, short-bunch beam. Recently, a new type of fast pulse generator, which utilized wideband rf amplifiers and a new chopper chamber with high-impedance strip-line electrodes, was developed to reliably and accurately cut out a short bunch from the long-pulsed beam emitted from a single-crystal CeB6 hot cathode. Using these apparatuses, we succeeded in forming nanosecond multibunch structure in the thermionic electron beam and generating a double-bunch XFEL pulse with a total pulse energy of 1 mJ at 10 keV. The results will provide new possibilities for XFEL beams: higher intensity, higher coherence, and higher pulse repetition rate.

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Phys. Rev. Accel. Beams 29, 093401– Published 9 September, 2026
  • Received 29 April 2026
  • Accepted 7 August 2026
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