Flux and energy of deuterium incident on a limiter-like probe in PLT

Carbon samples were exposed to the plasma edge in the PLT tokamak at various distances from the plasma. The amount of deuterium retained was subsequently determined using nuclear reaction analysis. The deuterium retention was found to saturate with increasing exposure time. Values for the energies and fluxes of the deuterium incident on the samples were determined by comparing the observed retention behavior with a saturation model for the retention. The deuterium fluxes and energies were found to decrease from ø~4 × 10¹⁷ D/cm² s and kT~270 eV at the radius of the limiter to ø~0.8 × 10¹⁷ D/cm² s and kT~90 eV at the radius of the wall. At these energies the fraction of the incident deuterium directly reflected from carbon is predicted to be 30 to 40%. From the deuterium energies and fluxes, values for the power flux and erosion rates are estimated.