A molecular dynamics study of diamond exposed to tritium bombardment for fusion applications

摘要

Diamond, with its low atomic number and high thermal conductivity, is being assessed as a possible plasma facing material within a fusion reactor. Molecular dynamics simulations using the A1REBO poten tial were performed simulating the exposure of diamond to a plasma in conditions similar to those of the divertor region of a tokamak. Diamond surfaces at temperatures of 300 and 600 K were bombarded with 15 eV tritium at a high flux (10~(29)ions m~(2) s~(1)). A layer-by-layer etching process was observed which, with the lack of any tritium diffusion though the remaining diamond structure, was responsible for lim iting damage, and thus tritium retention, to the top 4-5 diamond layers. Analysis of this damaged region also showed a large amount of residual structure suggesting that bombardment below the physical sput tering threshold (~30 eV) may not lead to amorphisation of the surface.