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SQUID-Based
Nondestructive Testing Equipment of Dished Niobium Sheets for SRF Cavities—AMAC
International, Inc., 12050 Jefferson Avenue, ARC, Suite 348, Newport News,
VA 23606-4385; 757-249-3595,
http://www.amacintl.com
Dr. Quan-Sheng Shu,
Mr. Ian
DOE Grant No. DE-FG02-05ER84141
Amount: $99,997
In superconducting cavities used
in nuclear physics research, the detection of impurities on to less than 50
micrometer sizes would enable the cavities to reach the highest possible
accelerating fields. Currently available
equipment can only inspect flat sheets, which allows for defective sheets to be
eliminated before the expensive forming and machining of the cavity
half-cells. However, this technology does
not eliminate the problem of impurities that may remain 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.
This project will develop nondestructive equipment that can scan dished niobium
sheets for superconducting radio frequency (SRF) cavities, allowing inspection
and detection during the entire cavity manufacturing process. The technology will be based on an existing,
sensitive SQUID (Superconducting Quantum Interference Device) system with gradiometer probe, non-magnetic dewar,
data acquisition system, and a three dimension tracing mechanical system. In Phase I, the detection sensitivity of the
SQUID pickup coils will be increased by modifying the existing flat-sample
scanning table to allow the system to scan curved surfaces. A two- dimensional inducer will be developed
to generate eddy currents in orthogonal directions. Finally, test scans will be
performed to verify the functioning of the system.
Commercial Applications and Other Benefits as described by the awardee: The instrument ultimately should allow the achievement of the highest possible accelerating field in cavities. In turn, the increased accelerating field would provide a considerable cost reduction for new accelerators as well as for upgrades of existing accelerators.