Magnetostatic field calculations associated with superconducting coils in the presence of magnetic material

A brief account is given of relevant magnetostatic field calculations in iron-free systems concerning the uniformity of the field produced by current-carrying axi-symmetric conductors. The effects of iron on the uniformity of the field produced by such a conductor are then considered. Using a perturbation analysis a simple analytic expression is obtained which describes the field close to the axis of symmetry. Some of the advantages of this method over traditional finite-difference methods are noted.