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Description
Tungsten (W) is the leading candidate material for plasma-facing components (PFCs) in future magnetic confinement fusion reactors, such as ITER and DEMO, due to its excellent properties. The PFCs will face extreme operating environments, including intense fluxes of high-energy particles, plasmas and heat, which will cause significant radiation damage and affect fuel retention.
This research performed high-energy proton irradiation experiments on a MeV radio frequency quadrupole (RFQ) accelerator and investigated the effects of proton irradiation on the deuterium (D) permeation and retention behavior in tungsten-based materials, including ITER-grade polycrystalline W, manufactured by Advanced Technology & Materials Co. Ltd Inc., China (ATW), 0.5 wt.% ZrC dispersion strengthened W (W-ZrC), and 2 wt.% Y2O3 dispersion strengthened W (W-Y2O3). The energy of the high-energy hydrogen ions was 0.75 MeV, with associated irradiation dose ranging from 0.01 dpa to 0.1 dpa. The samples were irradiated at room temperature and 773 K.
Microstructural analysis using transmission electron microscopy (TEM) revealed a high density of dislocation loops in the ATW after proton irradiation, indicating significant radiation damage that creates new trapping sites. Correspondingly, the D retention in ATW irradiated to 0.01 dpa was comparable to the unirradiated sample. However, the retention increased drastically by approximately one order of magnitude after 0.1 dpa irradiation, with thermal desorption spectroscopy (TDS) exhibiting multiple desorption peaks linked to various trap types. Furthermore, D permeation measurements showed that in the high-temperature regime with 1073 K and 1123 K, the D diffusion coefficient in the proton-irradiated ATW was slightly lower than that of the pristine material, a finding consistent with the enhanced trapping efficiency of the irradiation-induced defects. The irradiation damage and its effect on D permeation and retention in W-ZrC and W-Y2O3 was also examined. These results are crucial for accurately predicting fuel inventory, tritium consumption, and material lifetime in future magnetic confinement fusion devices.