The production of negative hydrogen and deuterium ions is studied in the Foundation for Fundamenteel Onderzoek der Materie surface conversion experiment. In this experiment a Barium surface is used to convert positive ions into negative ions. We have developed a detector able to analyze the characteristics of the surface produced negative ion beam. Measurements with this detector show that in barium surface conversion sources negative ions can be formed by recoiling and direct reflection of positive ions from the barium surface. The broad angular distribution of the surface produced negative ions is determined to extend over 16°.

J. Appl. Phys.

Heeren, R., de Graaf, M. J., Ciric, D., Hopman, H. J., & Kleyn, A. W. (1994). Angular and energy distributions of surface produced H- and D- ions in a barium surface conversion source. J. Appl. Phys., 75, 4340–4351.