Pulsed Eddy Current Testing Based on Gradient Magnetic Field Measurement

Gradient Magnetic Field Measurement (GMFM) has been intensively used in Magnetic Resonance Imaging (MRI). In this paper, we introduce GMFM to Pulsed Eddy Current Testing (PECT) in an effort to enhance the PECT sensitivity to subsurface anomalies in stratified conductors. The closed-form expressions of GMFM-based PECT signals have been formulated via the Extended Truncated Region Eigenfunction Expression (ETREE) modeling. Through theoretical investigation, it has been found that the new PECT technique is advantageous over the conventional PECT in terms of high sensitivity to subsurface material degradation.