Recent Progress in Ion Sources

This paper is intended to survey recent developments in ion sources, particularly work reported at the "Symposium on Ion Sources and the Formation of Ion Beams" held in Berkeley in October 1974. The approach here will be to subdivide this topic into three main areas; briefly list and discuss notable progress in each; and finally add some additional detail through a few specific, selected examples. The major items of progress discussed include development of large-area plasma surfaces for multiple-aperture ion sources, a significant increase in available negative-ion current densities, and improved general agreement between extraction electrode design and performance.