Integrated low-temperature superconductor SQUID gradiometers for nondestructive evaluation

Author

Klein, U. ; Walker, M.E. ; Carr, C. ; McKirdy, D.M. ; Pegrum, C.M. ; Donaldson, G.B. ; Cochran, A. ; Nakane, H.

Author_Institution

Dept. of Phys. & Appl. Phys., Strathclyde Univ., Glasgow, UK

Volume

7

Issue

2

fYear

1997

fDate

6/1/1997 12:00:00 AM

Firstpage

3037

Lastpage

3039

Abstract

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.

Keywords

SQUID magnetometers; eddy current testing; flaw detection; 70 Hz; Al; eddy current nondestructive evaluation; electromagnetically unshielded environment; integrated low-temperature superconductor SQUID gradiometer; magnetic field sensor; multilayered aluminum structure; subsurface flaws; Aluminum; Eddy currents; Interference; Magnetic sensors; Niobium; SQUIDs; Sensor phenomena and characterization; Sensor systems; Superconducting coils; Superconducting devices;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.621972

Filename

621972