Abstract
The stable configuration and shape of helium cluster in tungsten are investigated with molecular dynamics method. It is found that the configuration of helium cluster tends to form a near-spherical polyhedron. At high temperature, the Hen cluster for n < 100 have enough time to evolve into spherical structure even after coalescing between two helium clusters, while the big helium cluster could retain the rod-like or other shape for a long time. The formation mechanism of fuzz on tungsten surface is still unclear. Whether the shape of helium clusters is reasonable in simulations may have significant effect on the formation of fuzz. Our results provide important references for Monte Carlo simulations.