Abstract: An ion source includes a pair of pole elements, at least one shunt element, and at least one magnetic field producing element that produces a magnetic field. A gap is defined between the pole elements of the pair of pole elements. The at least one magnetic field producing element and the at least one shunt element cooperate to define at least a part of a magnetic field conducting circuit that conducts the magnetic field between the pole elements of the pair of pole elements. The pair of pole elements and the at least one shunt element are formed from a material that consists essentially of ferrous metal having an overall carbon content of less than 0.08 percent.