Author: Ciovati, G.
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WEYGBF3 Nb3Sn Multicell Cavity Coating at JLab 1798
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G. Ciovati, G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • I.P. Parajuli, MNS. Sayeed
    ODU, Norfolk, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
Following encouraging results with Nb3Sn-coated R&D cavities, the existing coating system was upgraded to allow for Nb3Sn coating of CEBAF accelerator cavities. The upgrade was designed to allow Nb3Sn coating of original CEBAF 5-cell cavities with the vapor diffusion technique. Several CEBAF cavities were coated in the upgraded system to investigate vapor diffusion coatings on extended structures. Witness samples coated along with the cavities were characterized with material science techniques, while coated cavities were measured at 4 and 2 K. The progress, lessons learned, and the pathforward are discussed.
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THPAL134 Commissioning of the Prototype C75 Cavities in a CEBAF Cryomodule 3961
  • M.A. Drury, G. Cheng, G. Ciovati, E. Daly, G.K. Davis, J. Guo, R.A. Legg, F. Marhauser, T. Powers, A.V. Reilly, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Prototype cavities have been built at Jefferson Lab to increase the energy of future refurbished CEBAF cryomodules to 75 MeV in the most cost efficient way. Three such cavities, named "C75", have been built from ingot Nb material of different purity and have been processed and tested. The two better performing cavities have been assembled into a "cavity pair" and installed in the latest refurbished original CEBAF cryomodule. The cryomodule was installed and commissioned in CEBAF. The results from the commissioning of the C75 cavities, compared with the original CEBAF cavities, are presented in this article. The vertical test performance of the C75 cavities was preserved in the cryomodule with one of the cavities achieving the performance specification of an accelerating gradient of 19 MV/m with a quality factor of ~8×109 at 2.07 K. The performance in terms of microphonics and tuner operation was similar to that of original CEBAF cavities, as expected, and the high-order modes are properly damped. The quality factor of the two C75 cavities was the highest achieved in a CEBAF cryomodule, possibly due to the better magnetic flux expulsion of ingot Nb than standard fine-grain Nb.
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