Progress of Helium Evolution in Aging Titanium Tritide Film

Helium release from titanium tritide films at room temperature have been studied. The evolution of lattice defects in long-aged titanium tritide films is also investigated by X-ray diffraction (XRD) over a period of about 1600 days (>4 years). And the thermal desorption (TD) has been used to investigate the ³He release from titanium tritide film with ³He/Ti atom ratio from 0.006 to 0.325. Results of XRD, TD and helium release were synthesized. A continuum-scale evolutionary model of helium for aging titanium tritide film is described which accounts for major features of the tritide experiment data. The combined stress-assisted-block loop punching growth for random bubble arrays and an average ligament stress criterion predicts an onset of inter-bubble fracture in good agreement with the He/Ti ratio observed for rapid He release.