An analytical model of eddy current ferrite-core probes

Abstract

An analytical model of an axisymmetric eddy current probe with a cylindrical ferrite core above a layered conductive half-space is developed. Initially we consider the magnetic vector potential of a circular filament coaxial with a ferrite core over a layered conducting half-space. The principle of superposition is then used to derive close-form expressions for both the electromagnetic field and the impedance of a coil from the filament field. Rather than locating the probe in infinite space, it is confined coaxially within a circularly cylindrical boundary on which the vector potential field is zero. The radius of this artificial boundary is large in order to ensure that does not interfere substantially with the field near the probe. By using a truncated region in this way, the vector potential in the probe region can be expanded as a series rather than an integral form. Thus the solution of the problem amounts to finding the expansion coeefficients in the series. Published by the American Institute of Physics. Related ArticlesExperimental demonstration of the equivalence of inductive and strongly coupled magnetic resonance wireless power transfer Appl. Phys. Lett. 102, 053904 (2013) Complete analytical solution of electromagnetic field problem of high-speed spinning ball J. Appl. Phys. 112, 104901 (2012) The influence of demagnetizing effects on the performance of active magnetic regenerators J. Appl. Phys. 112, 094905 (2012) The analysis of single-electron orbits in a free electron laser based upon a rectangular hybrid wiggler Phys. Plasmas 19, 093114 (2012) A high-performance magnetic shield with large length-to-diameter ratio Rev. Sci. Instrum. 83, 065108 (2012) Additional information on AIP Conf. Proc. ABSTRACT. An analytical model of an axisymmetric eddy current probe with a cylindrical ferrite core above a layered conductive half-space is developed. Initially we consider the magnetic vector potential of a circular filament coaxial with a ferrite core over a layered conducting half-space. The principle of superposition is then used to derive close-form expressions for both the electromagnetic field and the impedance of a coil from the filament field. Rather than locating the probe in infinite space, it is confined coaxially within a circularly cylindrical boundary on which the vector potential field is zero. The radius of this artificial boundary is large in order to ensure that does not interfere substantially with the field near the probe. By using a truncated region in this way, the vector potential in the probe region can be expanded as a series rather than an integral form. Thus the solution of the problem amounts to finding the expansion coefficients in the series. The numerical predictions of probe impedance have been compared with experimental data showing good agreement.