Development of an Electromagnetic Microscope for Eddy Current Evaluation of Materials

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Abstract:

Superconductive quantum interference devices SQUIDs offer new technology for locating material flaws electromagnetically that promises to increase sensitivity and depth of field as well as to enhance resolution and imaging. The ultrahigh sensitivity of SQUIDs to magnetic flux allows use of microscopic pickup loops in a gradiometer configuration to give high resolution. To realize the advantages of SQUID technology for Air Force requirements in evaluating the integrity of airframes, SQM Technology, Inc. is developing an electromagnetic microscope that uses an array of microscopic pickup loops for imaging micro flaws in aluminum. The prototype comprises a triangular array of microscopic gradiometers that are coupled to SQUID sensors through a flexible, cryogenic umbilical, which enables convenient scanning. Development to date shows three main accomplishments 1 a planar, azimuthal gradiometer configuration enables suppressing source interference, 2 instrument noise at drive currents of 1 A or so at frequencies below a few kilohertz is of the order of SQUID noise, and 3 a cryogenic umbilical can provide adequate cooling over a four to six foot length.

Author(s):
Podney, Walter N.
Author Organization(s):
SQM TECHNOLOGY INC LA JOLLA CA
Descriptive Note:
Annual technical rept.,
Pagination:
0024

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release
Distribution Statement:
Approved For Public Release; Distribution Is Unlimited.

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
SQMT-91-101R, AFOSR-TR-91-0785
Contract/Grant Number(s):
F49620-90-C-0058
Monitor Series:
TR-91-0785, AFOSR
 Subject Terms
Joint Capability Areas:
JCA_5_Command and Control; JCA_1_Force Support; JCA_5.5.2_Task; JCA_5.5_Direct; JCA_1.2_Force Preparation; JCA_5.3_Planning; JCA_1.2.3_Educating; JCA_3.2_Engagement; JCA_3_Force Application; JCA_6_Net Centric; JCA_6.1.1_Wired Transmission; JCA_3.2.1_Kinetic Means; JCA_JCA_4.1.2_Sustain the Force; JCA_4.1_Deployment and Distribution; JCA_6.3.3_Spectrum Management; JCA_1.3_Human Capital Management; JCA_6.1_Information Transport; JCA_8.2.1_Partner with Governments and Institutions; JCA_8.2_Shape; JCA_8_Building Partnerships
Communities of Interest:
Sensors
Descriptor(s):
*TEST AND EVALUATION, SOURCES, MAGNETIC FIELDS, AIR FORCE, MILITARY REQUIREMENTS, DETECTORS, FLUX(RATE), SUPERCONDUCTORS, SENSITIVITY, COOLING, HIGH RESOLUTION, DEPTH, MICROSCOPY, DEFECTS(MATERIALS), ALUMINUM, LENGTH, CONFIGURATIONS, IMAGES, PLANAR STRUCTURES, INTERFERENCE, AIRFRAMES, DRIVES, INSTRUMENTATION, QUANTUM ELECTRONICS, NOISE, MICROSCOPES, AZIMUTH, LOOPS, ELECTROMAGNETISM, CURRENTS, EDDY CURRENTS, FEET, GRADIOMETERS, CEPHALOPODA, COUPLING(INTERACTION)
Field(s)/Group(s):
Electrooptical and Optoelectronic Devices
Keyword(s):
*ELECTROMAGNETIC MICROSCOPES, SQUID(SUPERCONDUCTIVE QUANTUM INTERFERENCE DEVICES), SUPERCONDUCTIVITY, AIR FORCE
Report Date:
1991 Aug 01