• I. Vasserman, B. Berkes, J.Z. Xu
  ANL, Argonne
• J. Kvitkovitc
  Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava

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

Hall probe is the best way to do tuning and measurements of insertion devices. Horizontal Hall probe magnetic field measurements in the presence of a strong vertical magnetic field were tested in 1997. The next step of this investigation was reported at the 2004 FEL Conference. Hall probe horizontal field measurements in the presence of a vertical magnetic field are complicated due to the influence of the Planar Hall probe effect on the resulting Hall voltage. 2-axis Sentron Hall probe was used for the Linear Coherent Light Source devices. By positioning the Hall probe accurately in the vertical direction, the probe could be used for fast measurements and tuning of FEL devices. To eliminate the high sensitivity to the positioning of the probe, a new type of Hall probe, consisting of two sensors combined so as to cancel the influence of the PHE, was developed at the Institute of Electrical Engineering, Slovak Academy of Sciences. The results of tests done at the APS showed that it is not sensitive to vertical position and is 60 times less sensitive than a Bell probe to the angle between the Hall sensor current and the in-plane component of the field direction.

• 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.