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Sekutowicz, J. S.

Paper Title Page
TUPMN021 Status of Nb-Pb Superconducting RF-Gun Cavities 962
 
  • J. S. Sekutowicz, J. Iversen, D. Klinke, D. Kostin, W.-D. Moller, A. Muhs
    DESY, Hamburg
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • K. Ko, Z. Li, L. Xiao
    SLAC, Menlo Park, California
  • R. S. Lefferts, A. R. Lipski
    SBUNSL, Stony Brook, New York
  • T. Rao, J. Smedley
    BNL, Upton, Long Island, New York
  • P. Strzyzewski
    The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
  
  We report on the progress in the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead. Measured values of quantum efficiency for lead at 2K and the RF-performance of three half-cell niobium cavities with the lead spot exposed to high electric fields are reported in this contribution.  
TUPMS085 Photoemission Tests of a Pb/Nb Superconducting Photoinjector 1365
 
  • J. Smedley, T. Rao
    BNL, Upton, Long Island, New York
  • J. Iversen, D. Klinke, D. Kostin, W.-D. Moller, A. Muhs, J. S. Sekutowicz
    DESY, Hamburg
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • R. S. Lefferts, A. R. Lipski
    SBUNSL, Stony Brook, New York
  
  Funding: This work has been partially supported by the EU Commission, contract no. 011935 EUROFEL-DS5, US DOE under contract number DE-AC02-98CH10886.

We report recent progress in the development of a hybrid lead/niobium superconducting (SC) injector. The goal of this effort is to produce an all-SC injector with the SCRF properties of a niobium cavity along with the superior quantum efficiency (QE) of a lead photocathode. Two prototype hybrid injectors have been constructed, one utilizing a cavity with a removable cathode plug, and a second consisting of an all-niobium cavity arc-deposited with lead in the cathode region. We present the results of QE measurements on these cavities, along with tests of the effect of the laser on the cavity RF performance.

 
WEPMS042 Optimization of the Low-Loss SRF Cavity for the ILC 2439
 
  • Z. Li, L. Ge, K. Ko, L. Lee, C.-K. Ng, G. L. Schussman, L. Xiao
    SLAC, Menlo Park, California
  • T. Higo, Y. Morozumi, K. Saito
    KEK, Ibaraki
  • P. Kneisel
    Jefferson Lab, Newport News, Virginia
  • J. S. Sekutowicz
    DESY, Hamburg
  
  Funding: Work supported by DOE contract DE-AC02-76SF00515.

The Low-Loss shape cavity design has been proposed as a possible alternative to the baseline TESLA cavity design for the ILC. The advantages of this design over the TESLA cavity are its lower cryogenic loss, and higher achievable gradient due to lower surface fields. High gradient prototypes for such designs have been tested at KEK (ICHIRO) and JLab (LL). However, issues related to HOM damping and multipacting (MP) still need to be addressed. Preliminary numerical studies of the prototype cavities have shown unacceptable damping for some higher-order dipole modes if the typical TESLA HOM couplers are directly adapted to the design. The resulting wakefield will dilute the beam emittance thus reduces the machine luminosity. Furthermore, high gradient tests on a 9-cell prototype at KEK have experienced MP barriers although a single LL cell had achieved a high gradient. From simulations, MP activities are found to occur in the end-groups of the cavity. In this paper, we will present the optimization results of the end-groups for the Low-Loss shape for effective HOM damping and alleviation of multipacting. Comparisons of simulation results with measurements will also be presented.

 
WEPMS062 Development of a Superconducting Connection for Niobium Cavities 2484
 
  • P. Kneisel, G. Ciovati, J. S. Sekutowicz
    Jefferson Lab, Newport News, Virginia
  • A. Matheisen, W. Singer, X. Singer
    DESY, Hamburg
  
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177.

Several, partially successful attempts have been made to develop a superconducting connection between adjacent niobium cavities with the capability to carry up to 30 mT of the magnetic flux. Such a connection would be particularly of great benefit to layouts of long accelerators like ILC because it would shorten the distances between structures and therefore the total length of an accelerator with the associated cost reductions. In addition the superconducting connection would be ideal for a super-structure, two multi-cell cavities connected through a half wavelength long beam pipe providing the coupling. Two welded prototypes of super-structure have been successfully tested with the beam at DESY. The chemical treatment and water rinsing was rather complicated for these prototypes. We have engaged in a program to develop such a connection based on the Nb55Ti material. Several options are pursued such as e.g.a two-cell cavity is being used to explore the reachable magnetic flux for the TESLA like connection with a squeezed niobium gasket between the flanges. In this contribution we will report about the progress of our investigations.