Development of semi-portable DC-SQUID magnetometer

Author

Kandori, A. ; Ueda, M. ; Ogata, H. ; Kado, H.

Author_Institution

Superconducting Sensor Lab, Chiba, Japan

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2474

Lastpage

2477

Abstract

A semi-portable DC-SQUID magnetometer with a liquid helium continuous flow cryostat has been developed. The cryostat is 340 mm long and 50 mm in outer diameter. The pick-up coil is a co-axial, first order, differential type, 20 mm in diameter and 30 mm in baseline. The distance between the pick-up coil and the outer surface of the cryostat is 5 mm. It is easy to set this cryostat on the chest wall or on a human head. The cool down time is about 20 minutes, which is much shorter than that for a conventional storage Dewar. The white noise level, measured in a magnetically shielded room, is 8.7 fT//spl radic/Hz at 30 Hz. Noise at 1 Hz is about 30 fT//spl radic/Hz. Noise from temperature fluctuations (<9 mK) and drift (4.22 K /spl sim/ 4.55 K) is negligible. The consumption rate of liquid helium is 10 l/h. Here, the authors show the measurement of a magnetocardiogram in a magnetically shielded room.<>

Keywords

SQUID magnetometers; biomedical equipment; cryostats; magnetocardiography; 1 Hz; 20 min; 20 to 340 mm; 5 mm; chest wall; conventional storage Dewar; cool down time; human head; liquid helium continuous flow cryostat; magnetically shielded room; magnetocardiogram measurement; medical instrumentation; pick-up coil; semiportable DC-SQUID magnetometer; temperature fluctuations; white noise level; Coils; Fluid flow; Humans; Magnetic heads; Magnetic noise; Magnetic shielding; Magnetometers; Noise measurement; White noise;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403092

Filename

403092