Author: Jones, L.B.
Paper Title Page
TUPSO33 The Commissioning of Tess: An Experimental Facility for Measuring the Electron Energy Distribution From Photocathodes 290
 
  • L.B. Jones, R.J. Cash, B.D. Fell, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D.V. Gorshkov, H.E. Scheibler, A.S. Terekhov
    ISP, Novosibirsk, Russia
 
  ASTeC have developed a Transverse Energy Spread Spectrometer (TESS) – an experimental facility to characterise the energy distribution of electrons emitted by a photocathode. Electron injector brightness is fundamentally limited by the width of this distribution or energy spread, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread at source. TESS supports photocathode performance measurements at room and LN2-temperature under illumination from a range of fixed- and variable-wavelength light sources, allowing characterisation of both metal and semiconductor photocathodes. Preliminary work with GaAs* has shown that electron energy spread is dependent on the quantum efficiency (Q.E.) of the photocathode source, and TESS includes a piezo-electric leak valve to allow controlled degradation of the photocathode Q.E. whilst monitoring the energy spread of emitted electrons. This system offers huge potential to support future photocathode R&D work into a range of photocathode materials. Using GaAs photocathodes activated to high levels of Q.E. in our photocathode preparation facility**, we present commissioning results for TESS.
* Proc. IPAC ’12, TUPPD067, 1557-1559
** Proc. IPAC ’11, THPC129, 3185-3187