Study of thermal hydrogen atom interaction with undamaged and self-damaged tungsten

Retention of deuterium in undamaged and damaged polycrystalline tungsten exposed to thermal D beam was studied between 370 K and 500 K as a function of D fluence. Damaged samples were produced by W ion irradiation with damage concentration upto 0.89 displacements per atom. ERDA was used to follow near-surface H and D areal densities in situ during the exposure and the D depth profiles down to 6 mu m were extracted ex situ by NRA. Both methods give the same D concentration within the first 400 nm. D retention in undamaged and damaged W exposed to thermal (0.2 eV) atoms was observed for the first time. Retention in damaged W is found to be higher than in undamaged due to additional traps created by heavy W ion pre-irradiation. Isotope exchange at the surface and in the bulk of damaged W was also investigated in situ by ERDA at different sample temperatures. (C) 2013 Elsevier B.V. All rights reserved.