Author: Padamsee, H.
Paper Title Page
WEPPC116 Depth Distribution of Losses in Superconducting Niobium Cavities 2495
  • A. Romanenko, A. Grassellino, J.P. Ozelis
    Fermilab, Batavia, USA
  • H. Padamsee
    CLASSE, Ithaca, New York, USA
  In order to optimize performances of superconducting niobium cavities it is crucial to understand the structure of near-surface few tens of nanometers of the material. In particular, superconducting properties of niobium, which depend on the presence of impurities and/or defects, may be non-uniform in the magnetic field penetration depth. A few cavity experiments based on oxypolishing* and anodizing**,*** provided some insight into the problem, but the definitive understanding is not developed yet. In this contribution we report on the "depth profiling" of the near-surface RF layer using an alternative technique based on the hydrofluoric acid (HF) rinsing. Tumbled, electropolished and buffered chemical polished cavities have been investigated and tentative nanostructural interpretation is discussed.
* P. Kneisel, Proc. of the 1999 SRF Workshop, Santa Fe, USA
** G. Eremeev and H. Padamsee, Physica C 441 No. 1-2 (2006) 62
*** G. Ciovati, P. Kneisel and A. Gurevich, PRSTAB 10 (2007) 062002
WEPPC031 Completed Assembly of the Daresbury International ERL Cryomodule and its Implementation on ALICE 2272
  • P.A. McIntosh, M.A. Cordwell, P.A. Corlett, P. Davies, E. Frangleton, P. Goudket, K.J. Middleman, S.M. Pattalwar, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.A. Belomestnykh
    BNL, Upton, Long Island, New York, USA
  • A. Büchner, F.G. Gabriel, P. Michel
    HZDR, Dresden, Germany
  • J.N. Corlett, D. Li, S.M. Lidia
    LBNL, Berkeley, California, USA
  • G.H. Hoffstaetter, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich
    CLASSE, Ithaca, New York, USA
  • T.J. Jones, J. Strachan
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • R.E. Laxdal
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • D. Proch, J.K. Sekutowicz
    DESY, Hamburg, Germany
  • T.I. Smith
    Stanford University, Stanford, California, USA
  The completion of an optimised SRF cryomodule for application on ERL accelerators has now culminated with the successful assembly of an integrated cryomodule, following an intensive 5 years of development evolution. The cryomodule, which incorporates 2 x 7-cell 1.3 GHz accelerating structures, 3 separate layers of magnetic shielding, fully adjustable & high power input couplers and fast piezo tuners, has been installed on the ALICE ERL facility at Daresbury Laboratory. It is intended that this will permit operational optimisation for maximised efficiency demonstration, through increased Qext adjustment whilst retaining both effective energy recovery and IR-FEL lasing. The collaborative design processes employed in completing this new cryomodule development are explained, along with the assembly and implementation procedures used to facilitate its successful installation on the ALICE ERL facility.