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Title: Intrinsic emittance reduction in transmission mode photocathodes

High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer’s three-step model well describes the photoemission process; however, some photocathode characteristics such as their thickness have not yet been completely exploited to further improve the brightness of the generated electron beams. Here, we report on the emittance and QE of a multi-alkali photocathode grown onto a glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction in the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering during electrons’ transit towards the cathode surface. Due to this effect, we predict that thicker photocathode layers will further reduce the intrinsic emittance of electron beams generated by photocathodes operated in transmission mode.
Authors:
 [1] ; ORCiD logo [1] ;  [1]
  1. Cornell Univ., Ithaca, NY (United States). Cornell Lab. for Accelerator-Based Sciences and Education (CLASSE)
Publication Date:
Grant/Contract Number:
SC0014338; SC0011643; PHY-1416318
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 12; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Cornell Univ., Ithaca, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; Monte Carlo methods; semiconductors; electron gas; ultrafast electron diffraction; electromagnetic coils; phonon scattering; glass; photocathodes; quantum efficiency; leptons
OSTI Identifier:
1469694
Alternate Identifier(s):
OSTI ID: 1243144

Lee, Hyeri, Cultrera, Luca, and Bazarov, Ivan. Intrinsic emittance reduction in transmission mode photocathodes. United States: N. p., Web. doi:10.1063/1.4944790.
Lee, Hyeri, Cultrera, Luca, & Bazarov, Ivan. Intrinsic emittance reduction in transmission mode photocathodes. United States. doi:10.1063/1.4944790.
Lee, Hyeri, Cultrera, Luca, and Bazarov, Ivan. 2016. "Intrinsic emittance reduction in transmission mode photocathodes". United States. doi:10.1063/1.4944790. https://www.osti.gov/servlets/purl/1469694.
@article{osti_1469694,
title = {Intrinsic emittance reduction in transmission mode photocathodes},
author = {Lee, Hyeri and Cultrera, Luca and Bazarov, Ivan},
abstractNote = {High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer’s three-step model well describes the photoemission process; however, some photocathode characteristics such as their thickness have not yet been completely exploited to further improve the brightness of the generated electron beams. Here, we report on the emittance and QE of a multi-alkali photocathode grown onto a glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction in the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering during electrons’ transit towards the cathode surface. Due to this effect, we predict that thicker photocathode layers will further reduce the intrinsic emittance of electron beams generated by photocathodes operated in transmission mode.},
doi = {10.1063/1.4944790},
journal = {Applied Physics Letters},
number = 12,
volume = 108,
place = {United States},
year = {2016},
month = {3}
}