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 300K. Single ^3He atom diffuses by interstitial paths, whereas two ^3He atoms attract each other and can form a stable dimer, which pushes a Cu atom out of its original lattice site and occupies the vacancy. This dimer can catch another ^3He atom and form atrimer with an equilateral triangular structure.