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Mast, J.

Paper Title Page
WEPMS055 SQUID-based Nondestructive Testing Instrument of Dished Niobium Sheets for SRF Cavities 2469
  • Q. S. Shu, G. Cheng, I. M. Phipps, J. T. Susta
    AMAC, Newport News, Virginia
  • I. Ben-Zvi
    BNL, Upton, Long Island, New York
  • P. Kneisel, G. Myneni
    Jefferson Lab, Newport News, Virginia
  • J. Mast, R. Selim
    CNU, Newport News
  Funding: Acknowledgment: This work is supported by DOE grant DE-FG02-05ER84241

Currently available technology can only inspect flat sheets and allow the elimination of defective flat sheets before the expensive forming and machining of the SRF cavity half-cells, but it does not eliminate the problem of remaining or uncovered surface impurities after partial chemical etching of the half-cells, nor does it detect any defects that may have been added during the fabrication of the half-cells. AMAC has developed a SQUID scanning system based on eddy current technique that allows the scanning of curved Nb samples that are welded to make superconducting RF cavity half-cells. AMAC SQUID scanning system successfully located the defects (Ta macro particles about 100 mm diameter) in a flat Nb sample (top side) and was able to also locate the defects in a cylindrical surface sample (top side). It is more significant that the system successfully located the defects on the backside of the flat sample and curved sample or 3-mm from the top surface. The 3-D SQUID-based Nondestructive instrument will be further optimized and improved in making SRF cavities and allow inspection and detection during cavity manufacturing for achieving highest accelarating fields.