Microstructural evolution of irradiated tungsten: Ab initio parameterisation of an OKMC model

It is important to develop an understanding of the evolution of W microstructure under the conditions expected in the International Thermonuclear Experimental Reactor as well as the DEMOnstration Power Plant, Modelling techniques can be very helpful in this regards. In this paper, an object kinetic Monte Carlo code has been parameterised on ab initio calculations to model the behaviour of helium atoms implanted in tungsten, in the presence or not of the point defects created during the implantation. The slowing down of atomic helium in tungsten as well as the associated Frenkel Pair production is determined using the Marlowe code and is described in a paper companion to this one. The OKMC simulations indicate that He desorption results from a competition between the formation of mobile clusters and sessile ones, and it is thus very important to model correctly their spatial distributions as well as their properties.