Author: Jones, L.B.
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Energy Distribution and Work Function Measurements for Metal Photocathodes With Measured Levels of Surface Roughness  
  • T.S. Beaver, L.B. Jones, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S. Mistry
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  Funding: The work is part of EuCARD2, partly funded by the European Commission, GA 312453. Funded by the Science and Technology Facilities Council.
The minimum achievable emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source which is measureable as the mean longitudinal and transverse energy spreads in the photoemitted electrons. Reducing emittance in an accelerator driving a Free Electron Laser (FEL) delivers significant reduction in the saturation length for an X-ray FEL, reducing machine cost and increasing X-ray beam brightness. There are many parameters which affect the intrinsic emittance of a photocathode. Surface roughness is a significant factor*, and consequently the development of techniques to manufacture low roughness photocathodes with optimum emission properties is a priority for the electron source community. In this work, we present transverse energy distribution and work function measurements made using our TESS facility** for electrons emitted from copper and molybdenum photocathodes with differing levels of measured surface roughness.
* Proc. FEL '06, THPPH013, 583586
** Proc. FEL '13, TUPPS033, 290293
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The ALICE ERL - DC Photocathode Gun Commissioning  
  • L.B. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  The ALICE (Accelerators and Lasers In Combined Experiments) accelerator was the first ERL to be operated in Europe. ALICE was used to drive the UK's first Free-Electron Laser, generating infra-red light in the 4 - 20 micron range which was used in the development of pioneering cancer diagnostics. This talk will present an overview of the ALICE DC GaAs photocathode gun, and review the measured performance of the gun when it was operated in to a dedicated diagnostics beamline.  
slides icon Slides WEICCC002 [61.715 MB]  
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