Deep nondestructive testing using a bulk high T/sub c/ RF-SQUID

Author

Alzayed, N.S. ; Chang-Xin Fan ; Lu, D.F. ; Wong, K.W. ; Chester, M. ; Knapp, D.E.

Author_Institution

Dept. of Phys. & Astron., Kansas Univ., Lawrence, KS, USA

Volume

4

Issue

2

fYear

1994

fDate

6/1/1994 12:00:00 AM

Firstpage

81

Lastpage

86

Abstract

We report the utilization of a high T/sub c/ symmetric two-hole RF-SQUID (superconducting quantum interference device) operating at liquid nitrogen temperature as a gradiometer in nondestructive testing (NDT). This technology offers a possibility of solving simultaneously four requirements: sensitivity, penetration depth, resolution, and portability of the device. We used the simple dipole model, and showed that the signal attenuation in the near zone agreed with our experimental results and is less than that of a plane wave. In our experiment we used a low frequency current of 30 Hz and demonstrated that the amplitude of the signal was reduced only by 20% after the insertion of 1" (2.54 cm) of aluminum alloy plates between the mock crack and the SQUID in agreement with the theoretical calculations.<>

Keywords

SQUIDs; crack detection; high-temperature superconductors; magnetometers; 30 Hz; 77 K; bulk high T/sub c/ RF-SQUID; deep NDT; dipole model; gradiometer; liquid N temperature operation; nondestructive testing; penetration depth; portability; resolution; sensitivity; signal attenuation; superconducting quantum interference device; symmetric two-hole SQUID; Aluminum alloys; Attenuation; Frequency; Interference; Nitrogen; Nondestructive testing; SQUIDs; Signal resolution; Superconducting devices; Temperature sensors;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.291695

Filename

291695