Patent ID: 7807983

Claim:
An apparatus for reducing magnetic fields at an implant location, the system comprising: a corrector-bar assembly comprising a set of magnetic core members, a plurality of coils distributed along the set of magnetic core members, and connecting elements to connect ends of the set of magnetic core members with each other to form a rectangular corrector-bar configuration; wherein the set of magnetic core members are parallel with each other; wherein the plurality of coils comprises a central group of coils to generate a central magnetostatic potential, a first auxiliary group of coils positioned on a first side of the central group of coils, and a second auxiliary group of coils positioned on a second side of the central group of coils, wherein the first and second auxiliary group of coils generate a compensatory magnetostatic potential to add or subtract from the central magnetostatic potential so that a sum of magnetostatic potential along a length of the set of magnetic core members is zero; and wherein the rectangular corrector-bar configuration provides a desired magnetic field clamping action.