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Title: Measurements of tungsten migration in the DIII-D divertor

Abstract

An experimental study of migration of tungsten in the DIII-D divertor is described, in which the outer strike point of L-mode plasmas was positioned on a toroidal ring of tungsten-coated metal inserts. Net deposition of tungsten on the divertor just outside the strike point was measured on graphite sarnples exposed to various plasma durations using the Divertor Materials Evaluation System (DiMES) system. Tungsten coverage, measured by Rutherford Backscattering Spectroscopy (RBS), was found to be low and nearly independent of both radius and exposure time closer to the strike point, whereas farther from the strike point the W coverage was much larger and increased with exposure time. Depth profiles from RBS show this was due to accumulation of thicker mixed-material deposits farther from the strike point where the plasma temperature is lower. These results are consistent with a low near-surface steady-state coverage on graphite undergoing net erosion, and continuing accumulation in regions of net deposition. This experiment provides data needed to validate, and further improve computational simulations of erosion and deposition of material on plasma-facing components and transport of impurities in magnetic fusion devices. Such simulations are underway and will be reported later.

Authors:
 [1];  [1];  [1];  [2]; ORCiD logo [3];  [4]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Toronto, ON (Canada)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1477317
Alternate Identifier(s):
OSTI ID: 1483173
Report Number(s):
SAND-2018-10807J
Journal ID: ISSN 0031-8949; 668371
Grant/Contract Number:  
AC04-94AL85000; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physica Scripta
Additional Journal Information:
Journal Volume: T170; Journal ID: ISSN 0031-8949
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., and Stangeby, P. C. Measurements of tungsten migration in the DIII-D divertor. United States: N. p., 2017. Web. doi:10.1088/1402-4896/aa8d5a.
Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., & Stangeby, P. C. Measurements of tungsten migration in the DIII-D divertor. United States. doi:10.1088/1402-4896/aa8d5a.
Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., and Stangeby, P. C. Fri . "Measurements of tungsten migration in the DIII-D divertor". United States. doi:10.1088/1402-4896/aa8d5a. https://www.osti.gov/servlets/purl/1477317.
@article{osti_1477317,
title = {Measurements of tungsten migration in the DIII-D divertor},
author = {Wampler, W. R. and Rudakov, D. L. and Watkins, J. G. and McLean, A. G. and Unterberg, E. A. and Stangeby, P. C.},
abstractNote = {An experimental study of migration of tungsten in the DIII-D divertor is described, in which the outer strike point of L-mode plasmas was positioned on a toroidal ring of tungsten-coated metal inserts. Net deposition of tungsten on the divertor just outside the strike point was measured on graphite sarnples exposed to various plasma durations using the Divertor Materials Evaluation System (DiMES) system. Tungsten coverage, measured by Rutherford Backscattering Spectroscopy (RBS), was found to be low and nearly independent of both radius and exposure time closer to the strike point, whereas farther from the strike point the W coverage was much larger and increased with exposure time. Depth profiles from RBS show this was due to accumulation of thicker mixed-material deposits farther from the strike point where the plasma temperature is lower. These results are consistent with a low near-surface steady-state coverage on graphite undergoing net erosion, and continuing accumulation in regions of net deposition. This experiment provides data needed to validate, and further improve computational simulations of erosion and deposition of material on plasma-facing components and transport of impurities in magnetic fusion devices. Such simulations are underway and will be reported later.},
doi = {10.1088/1402-4896/aa8d5a},
journal = {Physica Scripta},
issn = {0031-8949},
number = ,
volume = T170,
place = {United States},
year = {2017},
month = {10}
}

Journal Article:
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