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The present work approaches the problem of determining, by analytical solutions, the electromagnetic field created by an arbitrary distribution of alternating currents placed outside an infinitely long non-magnetic conductive cylinder. Making use of the dyadic Green function method, the electromagnetic field outside the cylinder is expressed as the sum of the field in free space and the field created by the currents induced in the conductive cylinder. The general results we obtained are particularized for the analytical solutions describing the operation of an eddy current transducer with rotating magnetic field for the case of a conductive cylinder non-coaxial with the current source.

Pulse eddy currents are proposed as a nondestructive testing (NDT) technique to detect flaws in conductive structures with large thickness. The harmonic component of a pulse is rich, the pickup signal containing the amount of information corresponding to multifrequency analysis. Due to the short time length of the pulse, the amplitude of the excitation increases up to 100 times of the amplitude for an ac signal. Both direct simulation of pulse eddy-currents phenomena using an A-FEM-BEM code and neural networks-based inversion techniques are performed. Numerical results for the inversion of signals due to outer defects are shown.

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