Magnetostatic energy of paramagnetic particles in magnetic separators

A series expansion is obtained for the magnetostatic interaction energy of an infinitely long cylinder of arbitrary cross section, uniformly magnetized in a direction perpendicular to its long axis, and a spherical paramagnetic particle, in powers of the radius of the paramagnetic particle. For a cylinder of elliptic cross section magnetized in an arbitrary direction, the first three terms in this series are evaluated explicitly.