Helium desorption in 3He implanted tungsten at low energy

The behavior of helium in 3He implanted tungsten has been studied using Nuclear Reaction Analysis as a function of the post-implantation annealing temperature. Two different implantation conditions have been investigated: medium energy (60 keV), and low energy (0.3 keV), which exhibit drastically different helium release behavior. In the case of medium energy implantation, desorption starts from 1550 K and seems to be due to the dissociation of single helium–vacancy complexes (He–V1). At 1873 K the released fraction reaches 75% that suggests the presence of a second type of helium trapping site. In the case of low energy implantation, desorption is observed from 400 K (slightly above room temperature) and indicates the presence of shallow helium traps the nature of which is discussed. The released fraction of helium saturates at ∼60% at the temperature of 1473 K which could be due to helium trapping at single He–V1 complexes.