Final Technical Progress Report on "Plasma Surface Interactions: Predicting the Performance and Impact of Dynamic PFC Surfaces"
The objective of this project is to develop, and integrate, high-performance simulation tools capable of predicting plasma-facing component (PFC) operating lifetime and the impact of the evolving surface morphology of tungsten-based PFCs on plasma contamination, including the dynamic recycling of fuel species and tritium retention, in future magnetic fusion devices. Establishing a fundamental physical understanding and developing predictive capabilities of plasma-surface interactions (PSI) requires simultaneously addressing complex and diverse physics occurring over a wide range of length (Angstroms to meters) and time (femtoseconds to years) scales, as well as integrating extensive physical processes across the plasma–surface interface. This requires development of not only detailed physics models and computational strategies at each scale, but also algorithms and methods to couple them effectively in a way that can be robustly validated. Deploying these tools requires the continued development and coupling of leadership-scale computational codes to describe the boundary plasma and the evolving PFC surface, as well as a host of simulations that bridge disparate scales to address complex physical and computational issues at the plasma–surface interface in multi-component materials systems for magnetic fusion energy development beyond ITER. This project will enable discovery of the key physical phenomena controlling critical PFC performance issues, and the quantitative prediction of their impact on PFC performance during both steady-state and transient plasma conditions. Such phenomena include: (i) surface evolution in regions of either net erosion or net deposition; (ii) the impact of the evolving surface composition and roughness on the retention and recycling of hydrogenic fuel isotopes; (iii) the impact of dilute impurities on surface morphological evolution and plasma contamination; and (iv) the effects of high-energy neutron damage on surface properties that could influence helium/hydrogenic species retention and recycling. The outcome of this project will be a suite of coupled plasma and materials modeling tools, and a leadership class PFC simulator to predict PFC evolution and feedback to the boundary plasma both during steady-state plasma operation and transient events. Success in the proposed research tasks will enable the prediction of both plasma fueling and the sources of impurity contamination that impact core plasma performance, and will lay the foundation for understanding, designing, and developing the materials required to meet the performance objectives of future fusion reactors. Advanced capabilities for predictive modeling of plasma-facing component (PFC) surface morphological evolution and near-surface structural evolution are required for evaluation of tungsten (W) as a PFC in ITER’s divertor and improvement of its performance. Atomistically-informed, hierarchically developed and properly parameterized continuum-scale models that can efficiently access the spatiotemporal scales of PFC tungsten dynamical response enable such quantitative predictions of PFC structural and morphological evolution. Toward this end, the research conducted at UMass Amherst focused on the development of a materials property and defect interaction database that is required for constitutive modeling of the mechanical response of PFC tungsten and heat and mass transport in the near-surface region and on the surface of the PFC material, as well as the development and continuous upgrading of surface morphological evolution models which will improve significantly the predictive accuracy of our PFC tungsten evolution simulators. This effort is within the scale-bridging mission of the PSI-SciDAC center. Specific research tasks executed at UMass Amherst included: (1) Development of comprehensive databases for: (a) PFC tungsten mechanical, thermal, and transport properties (including elastic properties, mechanical strength, thermal conductivity, coefficient of thermal expansion, diffusion coefficients, and heats of transport); and (b) energetics of plasma-related defect interactions in the PFC near-surface region; (2) Incorporation of the above databases into constitutive models to determine the level of stress, as well as heat and species fluxes in PFC tungsten under plasma exposure conditions; (3) Developing and continuous upgrading of our hierarchical, atomistically-informed continuum-scale models of PFC surface evolution by incorporating additional physics modules (diffusion mechanisms, bubble dynamics) into the models; and (4) Computational implementation of the above databases, constitutive models, and upgraded surface dynamics in our simulators for predicting surface and near-surface dynamical response of PFC tungsten, from He retention to surface damaged (fuzz) layer growth as a function of fluence, under realistic plasma exposure conditions. The atomistic simulations involved in the database development employed state-of-the-art interatomic interaction potentials with excellent predictive capabilities. Our PSI-SciDAC kinetic Monte Carlo simulators, surface morphological evolution simulators, and the Xolotl PFC simulator are properly upgraded by integrating into their capabilities the above property database, constitutive information, and additional physics modules (from surface diffusion mechanisms to subsurface bubble dynamics).
- Research Organization:
- University of Massachusetts Amherst
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
- Contributing Organization:
- University of Tennessee Knoxville; Oak Ridge National Laboratory; University of Missouri Columbia; Clemson University; Pacific Northwest National Laboratory
- DOE Contract Number:
- SC0018421
- OSTI ID:
- 2279204
- Report Number(s):
- DE-SC0018421
- Resource Relation:
- Related Information: See related identifiers/DOIs below.
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
97 MATHEMATICS AND COMPUTING
Plasma-Surface Interactions
Plasma-Facing Components
Plasma-Facing Tungsten
Helium Implantation
Surface Physics
Surface Morphological Evolution
Plasma-related Structural Defects
Molecular-Dynamics Simulations
Molecular-Statics Computations
Cluster Dynamics Simulations
Multi-scale Modeling and Simulation