H− enhancement process in a multicusp ion source operated with a barium insert structure

Abstract
It has been demonstrated that the H output current from a small multicusp source can be substantially enhanced if the hydrogen plasma is seeded with barium. Operating with a barium washer insert at the extraction aperture, it is found that the extractable H current is increased by a factor of 3 if the insert bias potential is optimized. By use of a mixture of xenon and hydrogen gas, it is further demonstrated that the positive hydrogen ions are responsible for the observed H enhancement.