Integrated low-temperature superconductor SQUID gradiometers for nondestructive evaluation
- Klein, U.
- Walker, M.E.
- Carr, C.
- McKirdy, D.M.
- Pegrum, C.M.
- Donaldson, G.B.
- Cochran, A.
- Nakane, H.
Publication date
June 1997
DOI Publisher
Institute of Electrical and Electronics Engineers (IEEE) ISSN
1051-8223 Citation count (estimate)
6Abstract
We describe an eddy current nondestructive evaluation system using a low-temperature superconductor magnetic field sensor in an electromagnetically unshielded environment. The sensor comprises a niobium dc superconducting quantum interference device (SQUID) integrated with a first-order gradiometric pickup coil to reject spatially uniform interference fields but remain sensitive to flaw induced fields. We demonstrate its use in locating and mapping subsurface flaws in a multilayered aluminum structure using an eddy current excitation field at a frequency of 70 Hz, with no magnetic shielding around the specimen or cryostat
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