Advances in the Use of LTS and HTS SQUIDS in Electromagnetic NDE
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.
This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.
Department
Abstract
Of the electromagnetic sensors currently under investigation for nondestructive evaluation (NDE), the superconducting quantum interference device (SQUID) arguably has the greatest potential. The characteristics [1] which make it suitable for eddy current NDE are: high sensitivity even in large ambient fields (detection of sub-nT signals); operation from very low frequencies (a few Hz or less) to very high frequencies (potentially MHz) permitting detection of surface and subsurface flaws; and high spatial resolution. Spatial resolution is related to the physical size of the device, which is often less than 1 mm square, even when the need to maintain its other properties is taken into account. This often allows the SQUID to be treated theoretically and practically as an ideal point sensor. However, it must be operated in a cryogenic environment: low temperature superconductor (LTS) SQUIDs need liquid helium and liquid nitrogen (LN2) is needed even for high temperature superconductor (HTS) SQUIDs. This makes it difficult to reduce the specimen-to-sensor stand-off below approximately 1 mm.