Transient response of a driver-pickup coil probe in transient eddy current testing

Abstract Novel solutions that correctly incorporate all electromagnetic interactions arising in inductively coupled circuits are presented for the case of a coaxial driver and pickup coil probe encircling a long ferromagnetic conducting rod. The differential circuit equations are formulated in terms of the rod׳s impulse response using convolution theory, and solved by Fourier transform. The solutions presented here are the first to account for feedback between a ferromagnetic conductor and the driver and pickup coils, providing correct voltage response of the coils. Experimental results, obtained for the case of square wave excitation, are in excellent agreement with the analytical equations.