Author: Noakes, T.C.Q.
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THPMY017 A Comparison of Surface Properties of Metallic Thin Film Photocathodes 3691
  • S. Mistry, M.D. Cropper
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • A.N. Hannah, L.B. Jones, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  In this work physical vapour deposition magnetron sputtering has been employed to deposit metallic thin films onto Cu, Mo and Si substrates. The use of metallic thin films offers several advantages: (i) metal photocathodes present a fast response time and a relative insensitivity to the vacuum environment (ii) metallic thin films when prepared and transferred in vacuum can offer smoother and cleaner cathode surfaces. The photocathodes developed here will ultimately be used to drive NCRF guns such as that used in VELA and the proposed CLARA light source test facility. The samples grown on Si substrates were used to investigate the morphology and thickness of the film. The samples grown onto Cu and Mo substrates were analysed and tested as photocathodes in a surface characterisation chamber, where X-Ray photoelectron spectroscopy was employed to determine surface chemistry and a Kelvin probe apparatus used to determine work function. QE measurements were enabled using a 266 nm UV laser.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY017  
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THPOW016 Transverse Energy Spread Measurements from GaAs Photocathodes at Variable Wavelengths 3964
  • T.C.Q. Noakes, R. Beech, L.B. Jones, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H.E. Scheibler, A.S. Terekhov
    ISP, Novosibirsk, Russia
  The transverse energy spread spectrometer (TESS) is an instrument specially developed at Daresbury Laboratory to measure the intrinsic transverse and longitudinal energy distributions from photocathode materials. Early work on the instrument has focussed on its use for the characterisation of GaAs photocathodes such as those commonly used in DC photoinjectors. More recently work has been conducted to extend the range of materials which can be evaluated using this apparatus, in particular by incorporating a monochromated white light source. New results are presented using the white light source to measure the energy spread of a GaAs photocathode across a range of different wavelengths to evaluate how this changes with excess energy.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW016  
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THPOW019 Beam Characterisation and Machine Developments at VELA 3975
  • D. Angal-Kalinin, A.D. Brynes, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, B.D. Muratori, T.C.Q. Noakes, M.D. Roper, Y.M. Saveliev, D.J. Scott, R.J. Smith, E.W. Snedden, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.D. Barrett, C.P. Topping, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • C.S. Edmonds, F. Jackson, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.D. Muratori, Y.M. Saveliev, D.J. Scott, C.P. Topping, P.H. Williams, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  An overview is presented of developments on VELA (Versatile Electron Linear Accelerator), an RF photo-injector with two user stations at Daresbury Laboratory. Numerous commissioning, machine development, beam characterisation and user experiments have been completed in the past year. A new beamline and a dedicated multiuser station have been commissioned and the first experiments performed. A number of measures have been taken to improve the stability of machine by mitigating a phase drift, laser beam transport drift and a coherent ~1 Hz beam oscillation. The 6D phase space of the electron beam has been characterised through quad scans, transverse tomography and with a transverse deflecting cavity.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW019  
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