Electrode Shaping for Ion and Electron Extractors

A technique has been developed that defines the shapes of electrodes needed to produce a good-quality cylindrically symmetric beam of ions or electrons. This work was motivated by the need to optimize electrode shapes for a high-brightness, low-energy, deuteron injector. Our experience had indicated that correct shaping of electrodes becomes increasingly important as beam perveance increases. This provided the motivation for developing a computer program that could specify electrodes producing optimum or improved beam quality. Several techniques have been developed and evaluated. The procedure described here has been very successful in meeting our design goals.