Overview of SQUID NDE

The Vanderbilt NDE (Non-Destructive Evaluation)
group is unique in its breadth of experience with SQUID magnetometers, and in the imaging and modeling of magnetic fields produced by widely varied sources. Besides imaging the magnetic fields due to current distributions in metals, such as induced eddy currents, thermal noise in conductors, displacement currents, currents due to ongoing corrosion, and persistent and applied currents in high Tc superconducting films, our group has imaged magnetic susceptibility of non-conductive materials, and remanent magnetization in geological samples and magnetically decorated surface flaws.

We have developed modeling algorithms for a wide range of NDE applications. The forward problems of field perturbation by a variety of flaw and sample geometry have been carried out either analytically or numerically. The inverse problems include deconvolution of magnetic field maps into a 2-D current distribution maps, and deconvolution into 3-D susceptibility distribution maps. We are also investigating a probability of detection model for SQUID NDE.

The NDE group has published over 70 journal articles, book chapters, and patents related to SQUID NDE, many of which are discussed in a comprehensive review article by Jenks. (W.G. Jenks, S.S.H. Sadeghi, and J.P. Wikswo, Jr., " SQUIDs for Non-Destructive Evaluation," J. of Physics D: Applied Physics, 30 293-323 (1997)). The mathematics of magnetic imaging for NDE is reviewed in a book chapter by Wikswo (J.P. Wikswo, Jr., "The Magnetic Inverse Problem for NDE," SQUID Sensors: Fundamentals, Fabrication and Applications, H. Weinstock, Ed., Kluwer Academic Publishers, The Netherlands, pp. 629-695, (1996)).