SQUID gradiometers for a fundamental study of underwater magnetic detection

Author

Hirota, M. ; Nanaura, K. ; Teranishi, Yuuichi ; Kishigami, T.

Author_Institution

Japan Defense Agency, Kawasaki, Japan

Volume

7

Issue

2

fYear

1997

fDate

6/1/1997 12:00:00 AM

Firstpage

2327

Lastpage

2330

Abstract

An LTS SQUID gradiometer measuring six elements of first order magnetic gradient was produced for a fundamental study of magnetic detection and localization under water. It was installed at the sea bottom shallower than 30 m and we measured magnetic noise which might degrade its detecting performance. Noise caused by the imbalance of the gradiometer pickup coils was suppressed by using an auxiliary three-axis SQUID magnetometer output. The imbalance parameters were determined by measuring geomagnetic variations surrounding the sea bottom. A test for the trial detection of an iron boat was conducted with the use of this gradiometer. The results obtained showed a high signal-to-noise ratio for the gradiometer.

Keywords

SQUID magnetometers; geomagnetic variations; magnetic field measurement; object detection; superconducting device noise; superconducting device testing; 23 m; LTS SQUID gradiometer; SQUID gradiometers; auxiliary three-axis SQUID magnetometer output; first order magnetic gradient; geomagnetic variations; gradiometer pickup coil imbalance; iron boat detection; magnetic dipole localization; magnetic noise; sea bottom; signal-to-noise ratio; target localization; underwater magnetic detection; Boats; Coils; Degradation; Geomagnetism; Iron; Magnetic noise; Noise measurement; SQUID magnetometers; Sea measurements; Testing;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.621705

Filename

621705