Effect of Surface Produced H⁻Ion on the Plasma Meniscus in Negative Hydrogen Ion Sources

This is the authors' abstract. We don't add key points for this paper.

To extract intense ion beams with good beam optics from ion sources, controlling the distance deff between the plasma meniscus (i.e., beam emission surface) and the beam extraction grid is important. This study conducts a novel investigation into the dependence of the effective distance deff on the amount of surface H- production SH-. For this purpose, a 3D PIC (three dimensional Particle-in-Cell) simulation is conducted to obtain a model geometry of the extraction region for a H- ion source with SH- as a parameter. Based on results, deff significantly depends on SH- and the H--electron density ratio (α = nH-/ne) in front of the extraction aperture for the same plasma density; as SH- increases, deff decreases. The results suggest that SH- is critical for controlling deff and the resultant beam optics extracted from the negative ion source.