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Focusing of relativistic electron beams with permanent magnetic solenoid

T. Xu1,*, C. J. R. Duncan1, P. Denham2, B. H. Schaap2, A. Kulkarni2, D. Garcia2, S. D. Anderson1, P. Musumeci2, and R. J. England1

  • *Contact author: txu@slac.stanford.edu
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Phys. Rev. Accel. Beams 28, 082401 – Published 20 August, 2025

DOI: https://doi.org/10.1103/phhz-fgnl

Abstract

Achieving strong focusing of MeV electron beams is a critical requirement for advanced beam applications such as compact laboratory x-ray sources, high gradient accelerators, and ultrafast electron scattering instrumentation. To address these needs, a compact radially magnetized permanent magnetic solenoid (PMS) has been designed, fabricated, and tested. The solenoid provides a compact and inexpensive solution for delivering high axial magnetic fields (1 T) to focus MeV electron beams. Field characterization of the solenoid demonstrates good agreement with analytical models, validating the PMS design. The electron beam test employs a high-brightness photoinjector to study the focusing properties of the PMS. The results indicate a focal length of less than 10 cm and a significant reduction in beam size with small spherical aberrations. Two application cases are evaluated: angular magnification in ultrafast electron diffraction setups and strong focusing for Compton scattering or other microfocus uses.

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Phys. Rev. Accel. Beams 28, 082401– Published 20 August, 2025
  • Received 30 April 2025
  • Accepted 30 July 2025
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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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