High resolution squid magnetometry for non-destructive evaluation. Final report, 1 September 1987-30 April 1993

Technical Report · Fri Apr 30 00:00:00 EDT 1993

OSTI ID:5768077

Wikswo, J P

Superconducting QUantum Interference Device (SQUID) magnetometers offer promise as multi-mode instruments capable of obtaining high resolution images of extremely low frequency injected currents or eddy currents, and they can be configured to image the magnetic susceptibility of titanium, aluminum and nonmetallic composites. While high resolution SQUID magnetometers will generally be noisier than conventional SQUIDs, the small coils and reduced coil-to-source spacing more than compensate to provide low-noise, high-resolution images. The high spatial resolution which can be obtained with SQUID magnetometers, the unparalleled sensitivity of SQUIDs at low frequencies, the ability to measure weak perturbations in strong applied magnetic fields, and the ability to discriminate against external sources of noise should make SQUID magnetometers well suited for NDE of deep flaws in aluminum and titanium aerostructures. To explore SQUID NDE, the authors have developed research facilities that include the high-resolution MicroSQUID magnetometer, a magnetic shield, a scanning stage, and a computer-based control and data acquisition system. Using this instrumentation, they have imaged magnetic fields produced by sources as varied as intrinsic currents due to corrosion or Johnson noise, remanent magnetization from ferromagnetic contamination, flaw-induced perturbations in either injected current or eddy currents induced by an AC field, Johnson noise currents in a copper ring, persistent currents in high transition-temperature superconductors, distributions of dia- or paramagnetism in an AC or DC magnetic field, and surface flaws decorated with a paramagnetic tracer.

• Research Organization: Vanderbilt Univ., Nashville, TN (United States). Dept. of Physics and Astronomy
• OSTI ID: 5768077
• Report Number(s): AD-A-268884/4/XAB; CNN: AFOSR-87-0337
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
47 OTHER INSTRUMENTATION
MAGNETOMETERS
PERFORMANCE TESTING
MATERIALS
NONDESTRUCTIVE TESTING
SQUID DEVICES
ALUMINIUM
COMPOSITE MATERIALS
CORROSION
EDDY CURRENTS
IMAGES
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
NOISE
SENSITIVITY
SPATIAL RESOLUTION
TITANIUM
CHEMICAL REACTIONS
CURRENTS
ELECTRIC CURRENTS
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FLUXMETERS
MAGNETIC PROPERTIES
MATERIALS TESTING
MEASURING INSTRUMENTS
METALS
MICROWAVE EQUIPMENT
PHYSICAL PROPERTIES
RESOLUTION
SUPERCONDUCTING DEVICES
TESTING
TRANSITION ELEMENTS
420500* - Engineering- Materials Testing
440800 - Miscellaneous Instrumentation- (1990-)