Comparison of deuterium retention for ion-irradiated and neutron-irradiated tungsten

The behavior of D retention for Fe ²⁺-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D ₂ thermal desorption spectroscopy (TDS) spectra for Fe ²⁺-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550 K increased as the displacement damage increased due to Fe ²⁺ irradiation increasing. In addition, the first desorption stage at 450 K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe ²⁺ irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D ₂ TDS spectra for Fe ²⁺-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.