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Title: Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D

Carbon deposition on tungsten between ELMs was investigated in DIII-D in semi-attached/detached H-mode plasma conditions using fixed outer strike point (OSP) positions. Carbon deposition during plasma exposure of tungsten was monitored in-situ by measuring the reflectivity of the tungsten sample surface. No significant carbon deposition, i.e., without strong variations of the reflectivity, was observed during these experiments including discharges at high densities. In contrast, ERO modeling predicts a significant carbon deposition on the tungsten surface for those high density plasma conditions. The surface reflectivity decreases with methane injection, consistent with increased carbon coverage, as expected. The sweeping of OSP leads to a pronounced increase of the surface reflectivity, suggesting that the strike point sweeping may provide an effective means to remove carbon coating from tungsten surface. The ERO modeling however predicts again a regime of carbon deposition for these experiments. In conclusion, the discrepancies between carbon deposition regime predicted by the ERO model and the experimental observations suggest that carbon erosion during ELMs may significantly affect carbon deposition on tungsten.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4]
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Univ. of California San Diego, La Jolla, CA (United States)
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698
Type:
Accepted Manuscript
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 12; Journal Issue: C; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
General Atomics; USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1460374

Guterl, J., Abrams, T., Ding, R., Guo, H. Y., Rudakov, D., and Wampler, W.. Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D. United States: N. p., Web. doi:10.1016/j.nme.2017.04.017.
Guterl, J., Abrams, T., Ding, R., Guo, H. Y., Rudakov, D., & Wampler, W.. Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D. United States. doi:10.1016/j.nme.2017.04.017.
Guterl, J., Abrams, T., Ding, R., Guo, H. Y., Rudakov, D., and Wampler, W.. 2017. "Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D". United States. doi:10.1016/j.nme.2017.04.017. https://www.osti.gov/servlets/purl/1460374.
@article{osti_1460374,
title = {Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D},
author = {Guterl, J. and Abrams, T. and Ding, R. and Guo, H. Y. and Rudakov, D. and Wampler, W.},
abstractNote = {Carbon deposition on tungsten between ELMs was investigated in DIII-D in semi-attached/detached H-mode plasma conditions using fixed outer strike point (OSP) positions. Carbon deposition during plasma exposure of tungsten was monitored in-situ by measuring the reflectivity of the tungsten sample surface. No significant carbon deposition, i.e., without strong variations of the reflectivity, was observed during these experiments including discharges at high densities. In contrast, ERO modeling predicts a significant carbon deposition on the tungsten surface for those high density plasma conditions. The surface reflectivity decreases with methane injection, consistent with increased carbon coverage, as expected. The sweeping of OSP leads to a pronounced increase of the surface reflectivity, suggesting that the strike point sweeping may provide an effective means to remove carbon coating from tungsten surface. The ERO modeling however predicts again a regime of carbon deposition for these experiments. In conclusion, the discrepancies between carbon deposition regime predicted by the ERO model and the experimental observations suggest that carbon erosion during ELMs may significantly affect carbon deposition on tungsten.},
doi = {10.1016/j.nme.2017.04.017},
journal = {Nuclear Materials and Energy},
number = C,
volume = 12,
place = {United States},
year = {2017},
month = {5}
}