Irradiation Effects on the Retention of Hydrogen in Al_2O_3

Substantial defects are produced in Al_2O_3 by 4 MeV Au ion irradiation with a fluence of 4.4\times10^15 cm^-2. Rutherford backscattering spectrometry/channeling and cross-sectional transmission electron microscopy methods are used to investigate the irradiation damage. The 190 keV H ions with a fluence of 1\times10^17 cm^-2 are used for implanting pristine and Au ion irradiated Al_2O_3 to explore the irradiation damage effects on the hydrogen retention in Al_2O_3. The time-of-flight secondary ion mass spectrometry method is used to obtain the single hydrogen depth profile and ions mass spectra (IMS), in which we find that implanted hydrogens interacted with defects produced by Au ion irradiation. In IMS, we also obtain the hydrogen retention at a certain depth. Comparing the hydrogen retention in different Al_2O_3 samples, it is concluded that the irradiation damage improves the tritium permeation resistance property of Al_2O_3 under given conditions. This result means that Al_2O_3 may strengthen its property of reducing tritium permeation under the harsh irradiation environment in fusion reactors.