DEGAUSSING WITH BEM AND MFS

Magnetic Shielding or degaussing is a special subclass of inverse magnetic field problems targeted at minimizing the signature of a magnetizable object placed in an external field. This is usually accomplished by placing an appropriate ''skin'' of current around or just inside the object. The problem is more demanding than the typical inverse problem in that the goal is to reduce the induced field everywhere outside the object, thus making the target cost function difficult to construct. Boundary Element Methods (BEM) can be formulated in terms of equivalent surface currents which are representative of the pattern of surface current necessary to minimize the signature. This paper investigates how and under what conditions this is so. In addition the paper examines the application of the Method of Fundamental Solutions (MFS) to the same problem. With MFS, the object cost function is integral to the formulation. Both methods am applied to simple two dimensional box structures placed in the Earth's field.