H− ion density measurement in a tandem multicusp discharge

Abstract

The H⁻ ion density is measured by photodetachment in the source and target sections of a tandem multicusp discharge containing a ‘‘magnetic filter.’’ The results confirm previous observations based on the measurement of extracted currents, that a magnetic filter, together with a small positive bias on the plasma grid, produce a significant increase in the H⁻ ion density and a reduction in the electron density in the target section.