Equivalent surface sources using the second order vector potential formulation

The method outlined is especially advantageous with eddy current problems, because it allows the interfaces of all conducting regions to be replaced with equivalent magnetic surface charge and surface current. These equivalent sources are an immediate result of the field computation, and require virtually no additional computation. In terms of these equivalent sources, external fields are found quite accurately from surface integrations. With boundary element method techniques, this ability is especially valuable in terms of its accuracy and speed in finding global quantities such as force. The equivalent sources are directly related to the second-order vector potential, which has separability advantages in a number of coordinate systems