• K.C. Harkay, Y.L. Li, K. Nemeth, R.A. Rosenberg, M. White
  ANL, Argonne
• L.K. Spentzouris
  Illinois Institute of Technology, Chicago, Illinois

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Future x-ray light sources such as FELs and ERLs impose requirements on emittance and bunch repetition rate that are very demanding on the electron source. Even if perfect compensation of space-charge effects could be attained, the fundamental cathode emission properties determine a lower bound on achievable source emittance. Development of ultra-low-emittance sources is a rapidly evolving area of R&D with exciting new results measured for low bunch charge, but it is very difficult to compare different results and quantify what works. The study of photocathodes, with the goal of optimizing for low emittance, is limited in scope. In this paper, we describe an R&D effort to systematically measure and design the fundamental properties of photocathodes suitable for an FEL or ERL. We plan to apply surface analysis lab techniques to characterize photoemission, and then correlate material properties with emittance. On the theory side, we plan to calculate electron band structure for crystal surfaces, correlate with lattice parameters and work function, and then estimate the transverse momentum using the three-step model. The status and results to date of this effort will be reported.

• M. White, J.T. Collins, P.K. Den Hartog, M.S. Jaski, G. Pile, B.M. Rusthoven, S.E. Shoaf, S.J. Stein, E. Trakhtenberg, J.Z. Xu
  ANL, Argonne

Funding: Work at Argonne was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No DE-AC02-06CH11357.

The Linac Coherent Light Source (LCLS), now being commissioned at the Stanford Linear Accelerator Center (SLAC) in California, and coming online for users in the very near future, will be the world’s first x-ray free-electron laser user facility. Design and production of the undulator system was the responsibility of a team from the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). A sophisticated, five-axis, computer-controlled support and motion system positions and stabilizes all beamline components in the undulator system. The system also enables undulators to be retracted from the beam by 80 mm without disturbing the rest of the beamline components. An overview of the support and motion system performance, including achieved results with a production unit that was reserved at Argonne for this purpose, is presented.