The Magnetic Field Gradiometer
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Authors
Fraser-Smith, A.C.
Subjects
Gradiometers
Magnetic Field Gradiometers
Magnetometers
Differe tial Magnetometers
MAD
Magnetic Field Gradiometers
Magnetometers
Differe tial Magnetometers
MAD
Advisors
Date of Issue
1983-02
Date
February 1983
Publisher
STAR Laboratory Department or Electrical Engineering Stanford University
Language
Abstract
This report has two principal goals: First, to present a general review of magnetic field
gradiometers and, second, to provide new data concerning these gradiometers, including new
information about their response to magnetic dipole fields. A system of nomenclature is introduced that is consistent with the mathematical concept of gradient and which provides a
basis for discussions of the different functions of magnetic field gradiometers and differential
magnetometers. The distinction between component gradiometers and total field gradiometers
is also stressed. An historical review provides an opportunity to describe the different characteristics of the many kinds of magnetic field gradiometers that have been developed since
the first report of such a gradiometer in 1925: rotating induction loop, fixed induction loop,
fluxgate, proton precession, optically pumped, and superconducting gradiometers are discussed.
It is pointed out how the great sensitivity of superconducting gradiometers, and possibly other
varieties of modern magnetic field gradiometers, may invalidate the popular 'source-free' asssumption under particular circumstances. Further, because these high sensitivities will make
the gradiometers more susceptible to the geomagnetic field gradient, expressions are derived
for the components of this gradient and some representative numerical values are calculated.
The response of both component and total field gradiometers to dipole sources is considered
for a number of different source-gradiometer configurations. On a more speculative note, two
varieties of rotating component gradiometers are discussed, with particular attention being
given to their possibly unique characteristics. The report ends by recapitulating the many
applications of magnetic field gradiometers, particularly in such important areas as medicine,
energy production, and defense, and by stressing the need for gradiometer-related basic research.
Type
Report
Description
Final Technical Report No. E723-1
Series/Report No
Department
Physics
Organization
Radioscience Laboratory Stanford Electronics Laboratories, Stanford University
Identifiers
NPS Report Number
Sponsors
Office of Naval Technology
Naval Postgraduate School
Office of Naval Research
Naval Postgraduate School
Office of Naval Research
Funder
N00228-81-C-AB56
Format
97 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.