Low energy and low fluence helium implantations in tungsten: Molecular dynamics simulations and experiments

Abstract

300 eV Helium implantation process into tungsten at 300 K has been studied with molecular dynamic simulations (MD). Predicted retention doses were compared to that obtained from experiments performed in equivalent conditions. A saturation phenomenon of the helium retention was evidenced for a number of impinging He atoms and a retention dose similar in both, experiments and simulations. From MD simulations it is learnt that observed Helium diffusion, formation and coalescence of clusters are the phenomena leading to the flaking of the substrate. These processes could explain the saturation of the Helium retention observed experimentally at low energies.

Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

“…a linear rise on a log-log scale followed by a saturation step, has already been reported by several authors [48][49][50]. In a previous work this experimental behavior has been compared to molecular dynamics simulation (MDs) of the implantation process, and a very good agreement was found [51]. The very low retention rate of He in W (about 10% in the linear part of the curve) can be related to its very high mobility inside the lattice when not trapped into defects like vacancies.…”

Substrate temperature and ion kinetic energy effects on first steps of He+ implantation in tungsten: Experiments and simulations

“…Complete description of the model and of the data treatment could be found in reference [13], we only give here the most important points of the simulation.…”

“…Such as described in the previous paragraphs and in our previous work, the course of a typical implantation run has been followed for 300 eV He atom kinetic energy and a W substrate temperature of 300 K by MD simulations [13]. Three steps have been evidenced when the number of implanted He atoms increases inside the W lattice:…”

“…This behavior was explained by the release of He atoms by cluster rupture and diffusion towards the surface [13].…”

“…In our previous work the mechanisms involved in the defect formation due to the retention of He in the W lattice have been investigated through experiments and MD simulations [13]. It has been…”