Molecular Dynamics Simulations of Helium Behaviour in Copper Crystals

Molecular dynamics simulations are performed to investigate the behaviour of helium atoms generated from tritium decay in perfect Cu crystals at 300 K. At the early stage just after a ³He atom generation, the lattice structure is badly deformed and the local temperature rises considerably above 300 K. Single ³He atom diffuses by interstitial paths whereas two ³He atoms attract each other and can form a stable dimmer, which pushes a Cu atom out of its original lattice site and occupies the vacancy. This dimmer can catch another ³He atom and form a trimmer with an equilateral triangular structure.