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Title: Sensitivity of WallDYN material migration modeling to uncertainties in mixed-material surface binding energies

The WallDYN package has recently been applied to a number of tokamaks to self-consistently model the evolution of mixed-material plasma facing surfaces. A key component of the WallDYN model is the concentration-dependent surface sputtering rate, calculated using SDTRIM.SP. This modeled sputtering rate is strongly influenced by the surface binding energies (SBEs) of the constituent materials, which are well known for pure elements but often are poorly constrained for mixed-materials. This work examines the sensitivity of WallDYN surface evolution calculations to different models for mixed-material SBEs, focusing on the carbon/lithium/oxygen/deuterium system present in NSTX. A realistic plasma background is reconstructed from a high density, H-mode NSTX discharge, featuring an attached outer strike point with local density and temperature of 4 × 10 20 m -3 and 4 eV, respectively. It is found that various mixed-material SBE models lead to significant qualitative and quantitative changes in the surface evolution profile at the outer divertor, with the highest leverage parameter being the C-Li binding model. Uncertainties of order 50%, appearing on time scales relevant to tokamak experiments, highlight the importance of choosing an appropriate mixed-material sputtering representation when modeling the surface evolution of plasma facing components. Lastly, these results are generalized to othermore » fusion-relevant materials with different ranges of SBEs.« less
Authors:
 [1] ;  [1] ;  [2]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Max-Planck-Institut fur Plasmaphysik, Garching (Germany)
Publication Date:
Grant/Contract Number:
AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 12; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
Max-Planck-Institut für Plasmaphysik, Garching, Germany
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1349234

Nichols, J. H., Jaworski, M. A., and Schmid, K.. Sensitivity of WallDYN material migration modeling to uncertainties in mixed-material surface binding energies. United States: N. p., Web. doi:10.1016/j.nme.2017.01.011.
Nichols, J. H., Jaworski, M. A., & Schmid, K.. Sensitivity of WallDYN material migration modeling to uncertainties in mixed-material surface binding energies. United States. doi:10.1016/j.nme.2017.01.011.
Nichols, J. H., Jaworski, M. A., and Schmid, K.. 2017. "Sensitivity of WallDYN material migration modeling to uncertainties in mixed-material surface binding energies". United States. doi:10.1016/j.nme.2017.01.011. https://www.osti.gov/servlets/purl/1349234.
@article{osti_1349234,
title = {Sensitivity of WallDYN material migration modeling to uncertainties in mixed-material surface binding energies},
author = {Nichols, J. H. and Jaworski, M. A. and Schmid, K.},
abstractNote = {The WallDYN package has recently been applied to a number of tokamaks to self-consistently model the evolution of mixed-material plasma facing surfaces. A key component of the WallDYN model is the concentration-dependent surface sputtering rate, calculated using SDTRIM.SP. This modeled sputtering rate is strongly influenced by the surface binding energies (SBEs) of the constituent materials, which are well known for pure elements but often are poorly constrained for mixed-materials. This work examines the sensitivity of WallDYN surface evolution calculations to different models for mixed-material SBEs, focusing on the carbon/lithium/oxygen/deuterium system present in NSTX. A realistic plasma background is reconstructed from a high density, H-mode NSTX discharge, featuring an attached outer strike point with local density and temperature of 4 × 1020 m-3 and 4 eV, respectively. It is found that various mixed-material SBE models lead to significant qualitative and quantitative changes in the surface evolution profile at the outer divertor, with the highest leverage parameter being the C-Li binding model. Uncertainties of order 50%, appearing on time scales relevant to tokamak experiments, highlight the importance of choosing an appropriate mixed-material sputtering representation when modeling the surface evolution of plasma facing components. Lastly, these results are generalized to other fusion-relevant materials with different ranges of SBEs.},
doi = {10.1016/j.nme.2017.01.011},
journal = {Nuclear Materials and Energy},
number = ,
volume = 12,
place = {United States},
year = {2017},
month = {3}
}