Electron-suppression experiments in a small multicusp H− source

Abstract

Several techniques for suppressing the electrons before they form part of the extracted beam have been studied in a small multicusp H− source. It is found that some schemes reduce both the electron and the H− output currents. Other approaches, such as the installation of a collar at the extraction aperture, the addition of xenon or cesium to the hydrogen discharge, or the reduction of the source plasma potential, not only can reduce the electron current substantially, but bring about an enhancement in the extracted H− current.