Simulation of defect build-up in tungsten during low energy irradiation.

Tungsten is the material chosen to be used in some of the most demanding parts of fusion test reactors and planned fusion power plants. The irradiation present will degrade the material over time, which lead to the need for component replacement. In order to understand the material degradation and to be able to predict the need for replacement, there is a need to understand how defects are produced in the material. Even though there will be high energy recoils in the material, there will be a substantial amount of recoils in the low energy regime. We study the effect of irradiation on the hundred eV scale and compare it to the commonly used Frenkel-pair insertion method. By conducting this investigation we can investigate if this insertion method is a possible speed up to full cascade simulations. These low energy simulations are also comparable with the energy given to recoils during electron irradiation. We found that the low energy cascades will produce damage as expected and that Frenkel-pair insertion will qualitatively give a similar result. However, we found, quantitatively in the form of clustering, that the results differ between methods, especially for the higher energies investigated. [ABSTRACT FROM AUTHOR]