Deuterium retention and blistering in tungsten foils

Abstract

To investigate deuterium retention and the onset of blistering, deuterium was implanted in cold rolled tungsten foils at fluences ranging from 3 ×1020 to 3 ×1022D/m2. Ion energies were 300eV and 2000eV in order to be below and above the tungsten theoretical damage energy threshold. While energy dependent phenomena were observed, blistering occurs regardless of ion energy. Both plastically and elastically deformed blisters were found, as manifest in before and after micrographs. The fraction of plastically deformed blisters did not saturate at the fluences used in these studies. However, the size of the largest blister that relaxed during TDS does saturate at ∼7µm. A simple conceptual model is presented, which proposes that the deuterium released from elastically deformed blisters appears at ∼600K in the thermal desorption spectra, which is consistent with large vacancy clusters.