Comparison of dynamic deuterium retention in single-crystal and poly-crystals of tungsten: The role of natural defects

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:461

Article

Ghiorghiu, F.¹  Minissale, M.¹  Hodille, E. A.¹  Grisolia, C.²  Angot, T.¹  Bisson, R.¹ 

[1] Aix Marseille Univ, CNRS, PIIM, Marseille, France

[2] CEA, IRFM, F-13018 St Paul Les Durance, France

关键词: Tungsten;    Deuterium;    Ion;    Plasma facing components;    Fusion;    Macroscopic rate equation;   

DOI  :  10.1016/j.nimb.2019.09.032

来源: Elsevier

【 摘 要 】

The time evolution of fuel retention in materials relevant for future fusion reactors is compared for two different tungsten microstructures: single-crystal versus recrystallized poly-crystals. The initial retention of both types of sample is similar. It decays exponentially with a time constant of similar to 18 h at 300 K (the so-called short-term retention). After 48 h at room temperature, a constant deuterium retention is measured (long-term retention) with the single-crystal containing systematically less deuterium than poly-crystals. Macroscopic rate equations models are built with density functional theory inputs to reproduce deuterium desorption observables with the MHIMS-R code. We found that the native oxide layer could explain the desorption peak located at similar to 450 K as well as most of the short-term retention in the single-crystal. The native oxide together with, dislocations for single-crystal and grain boundaries for poly-crystals, are responsible for the long-term retention. Dislocations should explain the desorption peak located at similar to 815 K for mechanically polished samples. The dual role of most of tungsten defects is related to their multi-trapping properties with filling-level-dependent detrapping energies. Finally, the use of an effective diffusivity of deuterium through the native oxide layer, i.e. its diffusion barrier character, is evaluated.

【 授权许可】

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