Integral law descriptions of quasistatic magnetic field shielding by thin conducting plates

A method is described for calculating the induced current distribution within a thin, nonferrous conducting plate with finite dimensions in the presence of an imposed magnetic field due to specified source conductors. The induced current solution is used to evaluate the resultant shielded magnetic field. In contrast with three-dimensional finite element descriptions, the method is applicable and computationally efficient for the complicated imposed field distributions that are typically present in practical shielding applications. Calculated results are compared with measured results for an experimental setup in which source conductors carry time-varying currents in opposite directions on one side of an aluminum plate, with the field magnitudes determined on the opposite (shielded) side of the plate. The calculated and measured results are in good agreement, both when the aluminum plate is present and when it is absent. This good agreement extends to regions where end effects yield very significant departure from the results of a 2-D finite element eddy current simulation.