Flux of hydrogen from tokamak devices

Energetic hydrogen ions which comprise tokamak plasmas are lost dominantly by the processes of charge exchange and plasma transport. The resulting outflux bombards surfaces at the plasma edge. Analysis of these particles gives information on the plasma properties such as ion temperature, particle confinement and heat transport, and on the plasma contamination mechanisms of sputtering and desorption. This paper presents recent results on the energy spectrum of ions and neutrals which impact the tokamak limiter and walls and discusses their importance to tokamak behavior. These experiments, performed with newly developed surface probes and time-of-flight detectors, show that the flux of ions at the plasma edge exceeds 1018 cm-2 s-1 at typical energies of 50 to 500 eV and that the flux of neutral hydrogen at the wall away from the limiter is typically 1014 cm-2 s-1 with average neutral energies of 200 eV. Modifications to currently used models of plasma recycling are proposed