ABSTRACT
This chapter describes the production of high-current H+/D+ and H-/D- ion beams by large-area multicusp sources. Large-area, multiple-aperture ion sources were first developed as ion thrusters for space exploration. These large-area multicusp sources have much in common. The converter surface is normally curved to geometrically focus the H- ions through the plasma to the exit aperture. In this type of source, the H- output current is directly proportional to the area of the converter. In the U. S. common long-pulse source (CLPS), the magnetic filter field must be superimposed to help the species mix. The U. S. CLPS provides a typical example of the large-area, multi-aperture ion source now being employed in the neutral beam injector system of all major tokamaks. Experimental investigations has been performed to develop large surface conversion D- sources with the use of barium metal for the production of multiampere D- beams for fusion applications.
