Spatially dependent cluster dynamics model of He plasma surface interaction in tungsten for fusion relevant conditions

Journal Article · Fri Dec 05 04:00:00 EST 2014 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/55/1/013014· OSTI ID:1348307

Faney, T. ^[1]; Krasheninnikov, Sergei I. ^[2]; Wirth, Brian D. ^[3]

---

1. Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering
2. Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering
3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

In fusion reactors, plasma facing components (PFC) and, in particular, the divertor will be irradiated with high fluxes of low-energy (similar to 100 eV) helium and hydrogen ions. Tungsten is one of the leading candidate divertor materials for ITER and DEMO fusion reactors. However, the behaviour of tungsten under high dose, coupled helium/hydrogen exposure remains to be fully understood. The PFC response and performance changes are intimately related to microstructural changes, such as the formation of point defect clusters, helium and hydrogen bubbles or dislocation loops. Computational materials' modelling results are described here that investigate the mechanisms controlling microstructural evolution in tungsten. The aim of this study is to understand and predict sub-surface helium bubble growth under high flux helium ion implantation (similar to 10²² m^-2 s^-1) at high temperatures (>1000 K). Here, we report results from a spatially dependent cluster dynamics model based on reaction-diffusion rate theory to describe the evolution of the microstructure under these conditions. The key input parameters to the model (diffusion coefficients, migration and binding energies, initial defect production) are determined from a combination of atomistic modelling and available experimental data. The results are in good agreement with results of an analytical model that is presented in a separate paper. In particular, it is found that the sub-surface evolution with respect to bubble size and concentration of the helium bubbles strongly depends on the flux and temperature.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
• DOE Contract Number: AC05-00OR22725; SC0002060
• OSTI ID: 1348307
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 1 Vol. 55; ISSN 0029-5515
• Publisher: IOP Science
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
cluster dynamics
fusion
helium
modelling
plasma facing materials
tungsten