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Mean transverse energy of electrons generated from mixed thermionic, multiphoton, and field emissions

Po-Hsun Wu (吳柏勳)1 and Yen-Chieh Huang (黃衍介)1,2,*

  • *Contact author: ychuang@ee.nthu.edu.tw
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Phys. Rev. Accel. Beams 28, 123402 – Published 9 December, 2025

DOI: https://doi.org/10.1103/scmd-7zgh

Abstract

The brightness of an electron emitter is fundamentally limited by the intrinsic emittance of the electrons born at a cathode. Different electron-emission mechanisms from a cathode give different values of mean transverse energy for calculating the intrinsic emittance of emitted electrons. This study reports a theory for calculating the mean transverse energy of electrons generated at a cathode via mixed thermionic, multiphoton, and field emissions. The theory successfully reveals the details of thermionically assisted multiphoton emission from a copper cathode excited by an intense infrared laser. An extension of the theory to calculate the intrinsic emittance and brightness of an electron emitter is also presented.

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Phys. Rev. Accel. Beams 28, 123402– Published 9 December, 2025
  • Received 19 June 2025
  • Accepted 13 November 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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