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Modelling of thermally enhanced erosion of beryllium

2005; Elsevier BV; Volume: 348; Issue: 3 Linguagem: Inglês

10.1016/j.jnucmat.2005.10.003

1873-4820

K. Schmid, M.J. Baldwin, R.P. Doerner,

Nuclear Materials and Properties

This paper presents two concurring models for the thermally enhanced erosion of metals. The modelling particularly deals with the erosion of beryllium by a helium plasma as an example system. Molecular dynamics (MD) simulations are used to reduce the number of free parameters in the models. A model of sublimation of ad-atoms created during ion impact was earlier proposed as an explanation of thermally enhanced erosion. Using MD calculations the parameter space for this model was reduced to a single free parameter, the areal surface defect density δDef. Using the reduced parameter space a very low δDef has to be assumed in order to reproduce the experimental observations. Therefore a new model is proposed here that is very similar to the ad-atom model but is based on a different mechanism to create weakly bonded surface atoms. The paper shows that inclusion of He atoms during exposure to high flux (1022 m−2 s−1) of low energy He (50 eV) leads to the formation of weakly bonded atoms in the surface. The comparison of both models with experimental data and their applicability to other projectile/target systems is discussed.