Effects of physical and chemical surface roughness on the brightness of electron beams from photocathodes

G. Gevorkyan, S. Karkare, S. Emamian, I. V. Bazarov, H. A. Padmore

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Abstract

The performance of free electron laser x-ray light sources, and systems for ultrafast electron diffraction and ultrafast electron microscopy, is limited by the brightness of the electron sources used. The intrinsic emittance, or equivalently, the mean transverse energy (MTE) of electrons emitted from the photocathode determines the maximum possible brightness in such systems. With ongoing improvements in photocathode design and synthesis, we are now at a point where the physical and chemical surface roughness of the cathode can become a limiting factor. Here we show how measurements of the spatially dependent variations in height and surface potential can be used to compute the electron beam mean transverse energy (MTE), one of the key determining factors in evaluation of brightness.

Original languageEnglish (US)
Article number092803
JournalPhysical Review Accelerators and Beams
Volume21
Issue number9
DOIs
StatePublished - Sep 14 2018
Externally publishedYes

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ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)
  • Surfaces and Interfaces

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