In accordance with one embodiment of the present invention, the ion-beam apparatus takes the form of an end-Hall ion source in which the detachable anode module incorporates the outer pole piece and includes an enclosure around the anode that both minimizes the loss of working gas and confines sputter contamination to the interior of this enclosure. This detachable anode module is substantially smaller than the entire end-Hall ion source, weighs substantially less, and can be duplicated for significantly less cost than the duplication of the entire ion source. In general, the components of the magnetic circuit determine the overall size, weight, and much of the cost of a gridless ion source. The reduced size, weight, and cost of the detachable anode module compared to the entire ion source is due to most of the magnetic circuit being excluded from the detachable module.