The present invention relates to an ion beam extraction assembly for use in an ion beam generation apparatus such as those used, for example, in an ion implanter. An ion beam extraction assembly is provided for mounting within an ion beam generating apparatus comprising an ion source such that the extraction assembly is operable to extract ions from the ion source as an ion beam. The extraction assembly comprises an electrode assembly separate from the ion source, an electrode of the electrode assembly defining at least partly a path through the extraction assembly for passage of an ion beam. At least a part of the electrode assembly adjacent the path is tungsten and at least a part of the electrode assembly that is remote from the path is formed from a less expensive and/or lighter material.