LARGE ION YIELDS IN HYDROGEN SCATTERING FROM A GRAPHITE SURFACE

In this article we report on surface scattering experiments at graphit e as to model the interactions at divertor surfaces in tokamaks and co nversion electrodes in negative ion sources. The formation of negative and positive hydrogen ions on a graphite surface during positive hydr ogenous ion scattering at a projectile energy of 400 eV is observed. A remarkably high H- and H+ ion fraction, both varying between 10% and 30% of ail scattered particles, is found during scattering of positive hydrogenous ions. (C) 1997 American Institute of Physics.