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High-brightness, symmetric electron bunch generation in a plasma wakefield accelerator via a radially-polarized plasma photocathode

J. Chappell1,†, E. Archer1,‡, R. Walczak1,2, and S. M. Hooker1,*

  • 1John Adams Institute for Accelerator Science and Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, United Kingdom
  • 2Somerville College, Woodstock Road, Oxford, United Kingdom

  • *Contact author: simon.hooker@physics.ox.ac.uk
  • †Present address: Met Office, Exeter, Devon, United Kingdom.
  • ‡Present address: Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
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Phys. Rev. Accel. Beams 28, 101301 – Published 3 October, 2025

DOI: https://doi.org/10.1103/hqqg-7rcd

Abstract

The plasma photocathode has previously been proposed as a source of ultrahigh-brightness electron bunches within plasma accelerators. Here, the scheme is extended by using a radially-polarized ionizing laser pulse to generate high-charge, high-brightness electron bunches with symmetric transverse emittance. Efficient start-to-end modeling of the scheme, from ionization and trapping until drive bunch depletion, enables a multiobjective Bayesian optimization routine to be performed to understand the performance of the radially-polarized plasma photocathode, quantify the stability of the scheme, and explore the fundamental relation between the witness bunch charge and its emittance. Comparison of plasma photocathodes driven by radially- and linearly-polarized laser pulses shows that the former yields higher-brightness electron bunches when operating in the optimally-loaded regime.

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Phys. Rev. Accel. Beams 28, 101301– Published 3 October, 2025
  • Received 19 May 2025
  • Accepted 11 September 2025
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