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A companion paper by Bretchko and Ludwig describes an open-loop pulsed hysteresis graph system that is capable of magnetizing ceramic and rare-earth permanent magnets such as neodymium, samarium cobalt, and Alnico in cylindrical and rectangular shapes. The prototype system relies on an air-core excitation coil with an inner diameter of 3 cm and a length of 10 cm. A pulsed power supply provides a transient current pulse of up to 9000 A into the air-core coil. The pulse duration is typically about 15-20 ms. In addition, a pair of Helmholtz coils records the applied magnetic field strength, whereas a local coil, tightly wound around the permanent magnet, records the magnetic flux density in the sample. Both fields are electronically acquired, digitized, and processed in a computer to obtain the hysteresis graph response of the sample. The processing allows compensation for the presence of the demagnetization field due to the open-loop system configuration. In this paper, we present an analytical approach to take into account the effect of permeability in cylindrical samples. Furthermore, we propose a numerical approach that can characterize conductive materials such as Alnico, whose eddy-current influence significantly affects the open-loop recording of the B-H curve. Index Terms--Demagnetization factor, eddy-current influence, hysteresis graph system, magnetic cylindrical samples, permanent magnets, pulsed field.

Development of a novel multistage numerical model of an electromagnetic acoustic transducer (EMAT), with particular emphasis on an EMAT receiver is presented. This model includes five separate modeling states, i.e. 1) static magnetic field simulation of an electromagnet, 2) pulsed eddy current distribution of a generic meander-line coil suspended over a conducting specimen, 3) Lorentz force distribution due to the interaction of the static magnetic field with the eddy current distributions, 4) acoustic wave generation and propagation based on the dynamic Lorentz forces, and 5) acoustic wave detection by an EMAT receiver. In particular, this paper describes how the transient particle displacement fields are converted into an induced voltage response as part of the EMAT receiver system. Numerical simulations show that the voltage response is dependent on the wire spacing of the receiver coil.