Abstract
Tungsten has been chosen as the plasma-facing wall material in fusion reactors, due to its high density and melting point. The wall material will not only be sputtered at the surface, but also damaged deep inside the material by energetic particles. We investigate the high-dose damage production and accumulation by computational means using molecular dynamics. We observe that the choice of interatomic potential drastically affects the evolution. The structure and stability of the obtained defect configurations are validated using a quantum-accurate Gaussian approximation potential.
Highlights
Tungsten has due to its high density and melting temperature been chosen as one of the materials to be used in parts of fusion reactors that are exposed to the highest heat and particle fluxes
The cascade simulations were carried out in a two step manner, with their own parameters; PKA simulation and relaxation simulation. These two steps were carried out 2000 times in the same simulation cell to accumulate damage and reach a dose of about 0.18 dpa, according to the NRT-equation [38,39,40] with a threshold displacement energy of 70 eV, without the arc-dpa correction [6,41]. 70 eV was chosen instead of the commonly used 90 eV for tungsten, as the experimental study used a similar value in their study [3]
We have investigated the high-dose damage production and evolution in tungsten by computational means using three different embedded atom method (EAM) potentials
Summary
Tungsten has due to its high density and melting temperature been chosen as one of the materials to be used in parts of fusion reactors that are exposed to the highest heat and particle fluxes These parts are the first wall material and the divertor of the reactor. A recent study by Reza et al [3] investigated the defect concentration as a function of dose in W at room temperature at both low and high doses They found, using Transient Grating Spectroscopy (TGS), that Frenkel pair saturation occurs at doses between 0.06 and 0.1 dpa, with defect fractions between 0.004 and 0.005, similar to what has been found previously in other metals [4,5,6]. Transmission Electron Microscopy (TEM) studies have been carried out on irradiated tungsten, and investigated the dislocation density evolution as a function of dose and tempera-
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