• D. Saez de Jauregui, S. Casalbuoni, A.W. Grau, M. Hagelstein, E.M. Mashkina
  FZK, Eggenstein
• R. Cimino, M. Commisso
  INFN/LNF, Frascati (Roma)
• R. Weigel
  Max-Planck Institute for Metal Research, Stuttgart

Recent investigations with the cold bore superconducting undulator installed at ANKA indicate that the main contribution to the beam heat load is caused by electron bombardment. For a quantitative understanding of the problem a cold vacuum chamber for diagnostics has been designed. Among other important parameters (heat load, pressure, etc) this device shall monitor the spectrum of the low energy electrons bombarding the wall. In this contribution we report on the measurements of the spectrum of the low energy electrons bombarding the wall of the cold vacuum chamber in a room temperature region of the ANKA storage ring performed using a in house developed retarding field analyzer (RFA). The calibration of the RFA performed at the national laboratories of Frascati is also described.

• E.M. Mashkina, A.J. Magerl
  University Erlangen-Nurnberg, Institute of Condensed Matter Physics, Erlangen
• C. Boffo, M. Borlein, W. Walter
  BNG, Würzburg
• S. Casalbuoni, A.W. Grau, M. Hagelstein, D. Saez de Jauregui
  FZK, Karlsruhe
• N. Vassiljev
  University Erlangen-Nuernberg, Institute of Condensed Matter Physics, Erlangen

A new 15 mm period, 1.5 m long planar undulator is being fabricated by Babcock Noell GmbH (BNG) for the ANKA synchrotron light source. In order to qualify the production process and to optimize both the quench protection scheme and the magnetic field correction system, a short prototype has been fabricated. The prototype has been tested in vertical configuration and liquid helium at 4.2K in the CASPER facility at ANKA. The magnetic field has been measured along the beam axis direction by Hall probes with a positioning precision of 3 μm. We report here on the field shimming scheme and the resulting performance of the coils.

• C. Boffo, M. Borlein, W. Walter
  BNG, Würzburg
• T. Baumbach, A. Bernhard
  KIT, Karlsruhe
• S. Casalbuoni, A.W. Grau, M. Hagelstein, R. Rossmanith
  FZK, Karlsruhe
• E.M. Mashkina
  University Erlangen-Nuernberg, Erlangen

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they allow increasing the flux and/or the photon energy with respect to permanent magnet IDs. Babcock Noell GmbH (BNG) is completing the fabrication of a 1.5 m long unit for ANKA at FZK. The period length of the device is 15 mm for a total of 100.5 full periods plus an additional matching period at each end. The key specifications of the system are: a K value higher than 2 and the capability of withstanding a 4 W beam heat load and a phase error of 3.5 degrees. In addition, during the injection phase of the machine, the nominal gap of 5 mm can be increased up to 25 mm. The magnets have been tested with liquid helium in a vertical dewar and are now being installed in the cryostat. This paper describes the technical design concepts of the device and the status of the assembly process.

• M. Hagelstein, T. Baumbach, S. Casalbuoni, A.W. Grau, B. Kostka, R. Rossmanith, D. Saez de Jauregui
  FZK, Karlsruhe
• A. Bernhard, D. Wollmann
  KIT, Karlsruhe
• J. Chavanne, P. Elleaume
  ESRF, Grenoble
• B. Diviacco
  ELETTRA, Basovizza
• E.M. Mashkina
  University Erlangen-Nurnberg, Institute of Condensed Matter Physics, Erlangen
• E.J. Wallén
  MAX-lab, Lund

Within the framework of a joint research activity of the European project IA-SFS (RII3-CT2004-506008) four synchrotron facilities have jointly developed diagnostic systems for superconducting undulators. Four work packages have been successfully completed: Design and construction of a test cryostat for field measurements; design and construction of a mock-up coil; field measurement and field error compensation; diagnostics and measurement of the spectrum of low energy electrons responsible for beam heat load in a superconducting undulator. The development advanced the knowledge of magnetic field error compensation considerably and might be of help in understanding the different beam heat load sources. Based on the development a second generation planar superconducting undulator with 15 mm period length for the synchrotron light source ANKA has been specified and procured.

• D. Wollmann, T. Baumbach, A. Bernhard, P. Peiffer
  KIT, Karlsruhe
• A.W. Grau, R. Rossmanith
  FZK, Karlsruhe
• E.M. Mashkina
  University Erlangen-Nuernberg, Erlangen

Recently a new concept for automatically reducing magnetic field errors in superconductive undulators was proposed. According to this proposal the field errors are compensated by an array of coupled high temperature superconductor loops attached to the surface of the superconductive undulator. The field errors induce currents in the coupled type II-superconducting loops and, as a result, the magnetic field generated by these currents minimizes the field errors. In this paper the results of a first successful experimental test of this concept are described.