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Iversen, J.

Paper Title Page
TUP034 Status of the 3rd Harmonic Systems for FLASH and XFEL in Summer 2008 471
 
  • E. Vogel, W. Decking, M. Dohlus, M.G. Hoffmann, M. Hüning, J. Iversen, K. Jensch, G. Kreps, T. Limberg, A. Matheisen, W.-D. Möller, K. Rehlich, A. Schmidt, J.K. Sekutowicz, W. Singer
    DESY, Hamburg
  • A. Bosotti, P. Pierini, D. Sertore
    INFN/LASA, Segrate (MI)
  • H.T. Edwards, E.R. Harms, T.N. Khabiboulline
    Fermilab, Batavia
 
 

Ultra short bunches with high peak current are required for the creation of high brilliance coherent light in the VUV and X-ray range in undulators. At the Free Electron Laser in Hamburg (FLASH) and the European X-ray free electron laser (XFEL) they are obtained by a two stage bunch compression scheme based on acceleration off the rf field crest and transverse magnetic chicanes. The deviation of the rf field's sine shape from a straight line leads to long bunch tails and reduces the peak current. This effect can be eliminated by adding a third harmonic rf system. The paper gives an overview on the actual status of the beam dynamical examinations and as well on the development of the third harmonic sub-systems like modules, cavities and radio frequency systems for FLASH and the XFEL.

 
THP019 Third Harmonic Superconducting Cavity Prototypes for the XFEL 821
 
  • P. Pierini, A. Bosotti, N. Panzeri, D. Sertore
    INFN/LASA, Segrate (MI)
  • H.T. Edwards, M.H. Foley, E.R. Harms, D.V. Mitchell
    Fermilab, Batavia
  • J. Iversen, W. Singer, E. Vogel
    DESY, Hamburg
 
 

The third harmonic cavities that will be used at the injector stage in the XFEL to linearize the rf curvature distortions and minimize beam tails in the bunch compressor are based on the rf structures developed at FNAL for the DESY FLASH linac. The design and fabrication procedures have been modified in order to match the slightly different interfaces of XFEL linac modules and the procedures followed by the industrial production of the main (1.3 GHz) XFEL cavities. A revision of the helium vessel design has been required to match the layout of the cryomodule strings, and a lighter version of the tuner has been designed (derived from the 1.3 GHz ILC blade tuner activities). The main changes introduced in the design of the XFEL cavities and the preliminary experience of the fabrication of three industrially produced and processed third harmonic rf structures are described here.