Use of a superconductive gradiometer in an ultrasensitive electromagnetic metal detector

Conference · Wed Mar 01 00:00:00 EST 1989 · IEEE Trans. Magn.; (United States)

OSTI ID:6090932

Czipott, P V; Podney, W N

The authors present a new instrument that we call an electromagnetic gradiometer. It uses a SQUID sensor as the receiver in an active, electromagnetic detector of nonferrous as well as ferrous objects. The gradiometer pickup loops sit in the center of magnet coils that generate a time-varying magnetic field inducing eddy currents in conductive bodies. The gradiometer measures the secondary magnetic field of the eddy currents. The SQUID's sensitivity at frequencies below 1 kHz makes electromagnetic metal detectors practical in the marine environment, where the electrical conductivity of seawater precludes conventional systems. The authors describe a prototype system that attains a detection range of 10 m in seawater for targets 50 cm in diameter. It operates at frequencies from 1 Hz to a few hundred Hz. Uses of the electromagnetic gradiometer include locating naval mines and undersea treasure. The system's response to seawater enables application to airborne electromagnetic bathymetry. On land, its sensitivity to crustal conductivity contrasts suits it to mineral exploration.

• Research Organization: Physical Dynamics, Inc., La Jolla, CA (US)
• OSTI ID: 6090932
• Report Number(s): CONF-880812-
• Journal Information: IEEE Trans. Magn.; (United States), Vol. 25:2; Conference: Applied superconductivity conference, San Francisco, CA, USA, 21 Aug 1988
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
SQUID DEVICES
FABRICATION
BATHYMETRY
EDDY CURRENTS
ELECTROMAGNETIC PULSES
MAGNET COILS
MAGNETIC FIELDS
PERFORMANCE
USES
CURRENTS
ELECTRIC COILS
ELECTRIC CURRENTS
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
PULSES
RADIATIONS
SUPERCONDUCTING DEVICES
420201* - Engineering- Cryogenic Equipment & Devices