Fast computation of quasi-static magnetic fields around nonperfectly conductive shields

A prediction model of low frequency, low impedance magnetic fields around conductive shield configurations in presence of arbitrary sources is proposed. The new model is based on the elimination of the shield barrier from the computational domain and consists in the application of impedance network boundary conditions (INBCs) on the shield surfaces which permits one to take into account the field discontinuity produced by the nonperfectly conductive region. The derivation of the INBCs on the shield surfaces is discussed in terms of the magnetic vector potential.