• H. Delsim-Hashemi, V. Miltchev, J. Roßbach
  Uni HH, Hamburg
• Y. Holler, A. Schöps, M. Tischer
  DESY, Hamburg
• I. Vasserman
  ANL, Argonne

A seeded free-electron laser (FEL) experiment at VUV wavelengths, called sFLASH will be installed at the existing SASE-FEL user facility FLASH until Spring 2010. Seed pulses at wavelengths around 30 nm and 13 nm from high harmonic generation (HHG) will interact with the electron beam in sFLASH undulators upstream of the existing SASE undulator section. In this paper, status of the sFLASH undulators are described.

• 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