Generation of Dust Seeds by Sputtering of Carbon-based Plasma Facing Materials under Low-energy H/D/T Ion Bombardment

Sputtering properties of graphite and amorphous carbon substrates by hydrogen (H), deuterium (D), and tritium (T) at low incident energies have been studied with the use of classical molecular dynamics (MD) simulations. The sputtering simulations used here are accumulative in the sense that the surface modification due to impinging species are self-consistently taken into consideration. The simulation results indicate that a high level of H/D/T dose accumulation on the top surface is prerequisite for the formation of relatively large-sized sputtered hydrocarbon products. Especially significant isotopic dependence of sputtering yields has been observed at the accumulation dose over 10 cm, which is qualitatively consistent with some of the earlier experimental results.