Mobile cryocooler-based SQUID NDE system utilizing active magnetic shielding

Author

Hatsukade, Yoshimi ; Inaba, Tomohiro ; Maruno, Yoshio ; Tanaka, Saburo

Author_Institution

Toyohashi Univ. of Technol., Aichi, Japan

Volume

15

Issue

2

fYear

2005

fDate

6/1/2005 12:00:00 AM

Firstpage

723

Lastpage

728

Abstract

A mobile cryocooler-based SQUID NDE system was developed for realization of NDE of fixed targets that can´t be moved or rotated. In order to move the SQUID in an ambient field, an active magnetic shielding technique employing a compensation coil and feedback circuit including a band elimination filter was introduced in a SQUID NDE system. The HTS SQUID gradiometer was cooled by a coaxial pulse tube cryocooler to 74 K ± 0.04 K. The flux noise caused by moving the SQUID at 32 mm/s was well suppressed. Unlocking of the flux-locked loop (FLL) circuit or a significant increase in noise did not occur during the motion. Detection of hidden slots in fixed single and double-layered carbon/carbon composites in ambient field was demonstrated by moving the HTS SQUID gradiometer.

Keywords

SQUID magnetometers; carbon fibre reinforced composites; low-temperature techniques; magnetic shielding; nondestructive testing; HTS SQUID gradiometer; active magnetic shielding; carbon-fibre composites; coaxial pulse tube cryocooler; flux-locked loop circuit; mobile cryocooler-based SQUID NDE system; Circuit noise; Coaxial components; Coils; Feedback circuits; Filters; High temperature superconductors; Magnetic noise; Magnetic separation; Magnetic shielding; SQUIDs; Active magnetic shielding; SQUID NDE; carbon-fiber composites; cryocooler; mobile;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2005.850026

Filename

1439740