BEM calculation for magnetic shielding with steel sheets

The Boundary Element Method (BEM) is adapted to the solution of two-dimensional and axisymmetrical nonlinear shielding problems. The high vector-field accuracy attainable permits studies of extremely uniform nuclear magnetic resonance (NMR) fields to be made as well as less demanding shielding calculations. A technique is described in which nonlinearities are replaced by virtual sources in an explicit iteration scheme. All unknowns are on boundaries only and matrix size is not increased due to interior nonlinearities. An example is given. Suggestions for efficiency improvements are made.