H− production from a barium converter with different discharge configurations

The production of H− ions at a barium converter immersed in a hydrogen plasma has been investigated experimentally for a pulsed discharge. It is found that the scaling of the negative ion output with incident positive ion current on the converter depends greatly on the actual geometry of the plasma generator. A less than linear scaling is observed in a multicusp system. A more than linear scaling is obtained in a configuration where the filament and the converter are separated by a permanent magnet filter.