Negative hydrogen production at a graphite surface

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.