A model of cup-core probe for eddy current nondestructive evaluation

Eddy current techniques are widely used for NDE of metallic objects. However, analytical solutions for eddy current problems are rather difficult to obtain. For some 2D plane geometries problems, where specific properties are assigned to layers of space and with an axisymmetric air coil excitation, partial differential equations solving by separation of variables is possible. The modeling of a realistic configuration, including a magnetic-core, gets significantly more complex, except for some particular cases. In this paper, we present an original solution based on flux ring excitation, allowing the analytical determination of the probe impedance. The studied geometry is a cup shaped ferrite core, with introduction of a conductive shielding, in order to reduce magnetic leakage and improve spatial resolution. The model is then validated by a finite element simulation