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  • Open Access

Collective and surface charge effects in high-brightness ultrafast electron sources

Anahita Omoumi1,*, Miguel M. Calderon1, Lee Jones2, Andrea Latina1, and Eduardo Granados1,†

  • *Contact author: anahita.omoumi@cern.ch
  • †Contact author: eduardo.granados@cern.ch
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Phys. Rev. Accel. Beams 29, 063401 – Published 29 June, 2026

DOI: https://doi.org/10.1103/c5zh-6xsv

Abstract

We present a photoemission model based on the Fowler-DuBridge equation that accounts for the dynamic modulation of the Schottky barrier during the emission of high-charge-density electron bunches. By incorporating the time-dependent effective electric field normal to the photocathode surface (including real-time emission-induced electric fields), our model captures the ultrafast transient modulation of the electron emission potential barrier that governs the instantaneous current density. This approach links single-electron photoemission effects with macroscopic collective charge effects, enabling accurate predictions of the time-dependent charge production for high-brightness photoinjectors. Furthermore, we validate the model by comparing it with the experimental results obtained with a high-gradient photoinjector equipped with ultraviolet pulse shaping capabilities. Our model highlights the importance of dynamic surface effects in shaping the initial phase space of electron bunches. The effects are particularly relevant for future lepton colliders where producing on-demand bunch charge with a tailored phase space is required, including the top-up injection scheme for CERN’s Future Circular Collider (FCC).

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Phys. Rev. Accel. Beams 29, 063401– Published 29 June, 2026
  • Received 16 December 2025
  • Accepted 22 May 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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