Surface Evolution in Long-Term Simulations of Graphite Boronization

Boronization has been shown experimentally to improve deuterium retention in fusion devices, which in turn leads to improvements in device performance. Prior simulations of boronization of graphite, a common wall material, have used randomized initial atomic positions, thus a concrete understanding of amorphization processes in crystalline graphite is necessary. Thus, in this study, the molecular dynamics (MD) code LAMMPS was used to bombard a large graphite structure with atomic boron over a range of impact energies. Then, from the simulation output, the number densities of boron and carbon as a function of depth were extracted to use as a metric for accumulated amorphization over time. Simulations show that larger impact energies lead to a greater degree of amorphization, shown by the increase in crosslinking between layers. Furthermore, the relationship between impact energy and amorphization timescale was investigated.