A study of helium bubble production in 10Â keV He+ irradiated tungsten

Helium bubble production in tungsten has been studied combining transmission electron microscopy and in situ irradiations with 10 keV He+ ions. The irradiations were carried out at four temperatures (773 K, 1073 K, 1273 K, 1473 K), and were held at intervals of (0.45; 0.9; 1.2; 1.5) × 1020 He+/m2 for each temperature. Based on detailed analyses of bubble size, population and spatial distributions, their correlations with irradiation temperature and helium fluence were established. Helium-to-vacancy ratios were also deduced from these data. During high temperature equilibrium, the ratio was close to 3.