Active compensation of magnetic field distortions based on vector spherical harmonics field description
Résumé
An analytic solution to the magnetostatic inverse problem in the framework of vector
spherical harmonic basis functions is presented. This formalism is used for the
design of a spherical magnetic field compensation system and its performance is
compared with an already existing rectangular coil system. The proposed set of
spherical coils with 15 degrees of freedom achieves a shielding factor of 1000
or better in a large part of the volume enclosed by the coils for a dipolar type
external perturbation.