• Y. Li, W. Decking, B. Faatz, J. Pflüger
  DESY, Hamburg

At the European XFEL circular polarized radiation in the wavelength range 0.4-1.6 nm is highly desired. An economically and technically convenient method is to utilize a long planar undulator to pre-bunch electron beam first and then pass it through a shorter and specially designed undulator to generate arbitrary polarized radiation. Between these two parts, the electrons and the radiation from the long undulator must be spatially separated by a bend. In this paper, a solution for an isochronous bend is presented considering nonlinear aberrations, which preserves theμbunching even for the 0.4 nm case.

• F. Hellberg, H. Danared, A. Hedqvist
  MSL, Stockholm
• Y. Holler, B. Krause, A. Petrov, J. Pflüger
  DESY, Hamburg

A rotating coil system has been set-up at the Manne-Siegbahn Laboratory to characterize the XFEL undulator quadrupoles with respect to magnetic center stability. In combination with a coordinate measuring machine the position of the magnetic center with respect to fiducials is measured. The rotating coil system has previously been used to measure the magnetic center stability with respect to magnet excitation for two prototype magnets with yokes of different materials [1]. That work has now been extended to a third material for the yoke. Here the results from measurements of the prototype magnets are presented together with results from test measurements performed to determine the accuracy of the fiducialization process.

[1] F. Hellberg et al, "Investigation of Quadrupole Magnets for the XFEL Project Using a Rotating Coil Set-up", FEL08, TUPPH044, Gyeongju, Korea, 2008