In this paper we report surface scattering experiments on graphite in an attempt to investigate fundamental charge exchange processes on divertor surfaces in plasma devices. A remarkably high H- ion fraction (10-20%) as a function of outgoing angle of the scattered particles is found during scattering of positive hydrogenous ions (H+, H2+ and H3+). These results cannot be explained with conventional theories of charge transfer.

K. Prelec

Tsumori, K., Koppers, W. R., Heeren, R., Kadodwala, M., Kleyn, A. W., & Beijersbergen, J. H. M. (1996). Negative hydrogen production at a graphite surface. In K. Prelec (Ed.), Production and Neutralization of Negative Ions and Beams : 7th Int. Symp. , Production and Application of Light Negative Ions : 6th European Workshop, A Joint Meeting, Upton, NY October 1995 (pp. 36–40).