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

Highlights: • TEM observation of helium bubbles in tungsten required a threshold fluence of ∼4.5 × 10¹⁹ He⁺/m² (He-peak: 10,800 appm). • Temperature has a pronounced impact on bubble size and population. At T ≥ 1273 K, 1D-alignment of bubbles was observed, suggesting a small degree of spatial ordering. • Helium fluence exhibited limited impact on bubble size at T • During high temperature equilibrium, the average configuration of helium-vacancy complexes is He_3mV_m (m ≥ 1). - Abstract: 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.