Improvement of the Film Eddy Current Sensors

Abstract

Previously, we have succeeded in exploiting a new high sensibility eddy current testing (ECT) sensor called the infinite (∞) coil. In addition, this paper proposes the other new ECT sensor to realize a further high sensibility sensor than those of our previous one. The new sensor utilizes the magnetic fields in the parallel directions to a tested target surface, and this makes it possible to construct a shape whose sensing coil could be entirely surrounded by the exciting coil. Surrounding the sensing coil entirely by the exciting coil makes it possible to work the exciting coil as if a shielding coil to the external electromagnetic noise. Thus, good signal to noise ratio is expected and has been confirmed by the numerical simulations as well as practical experiments.