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Title: Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER

Abstract

The free-streaming plus recycling model (FSRM) has recently been developed to understand and predict tungsten gross erosion rates from the divertor during edge localized modes (ELMs). In this work, the FSRM was tested against the experimental measurements of W sputtering during ELMs, conducted via fast neutral tungsten (WI) spectroscopy. Good agreement is observed using a variety of controlling techniques, including gas puffing, neutral beam heating, and plasma shaping to modify the pedestal stability boundary and, thus, the ELM behavior. ELM mitigation by pellet pacing was observed to strongly reduce W sputtering by flushing C impurities from the pedestal and reducing the divertor target electron temperature. No reduction of W sputtering was observed during the application of resonant magnetic perturbations (RMPs), in contrast to the prediction of the FSRM. Potential sources of this discrepancy are discussed. Lastly, the framework of the FSRM is utilized to predict intra-ELM W sputtering rates in ITER. It is concluded that W erosion during ELMs in ITER will be caused mainly by free-streaming fuel ions, but free-streaming seeded impurities (N or Ne) may increase the erosion rate significantly if present in the pedestal at even the 1% level. Impurity recycling is not expected to cause criticalmore » W erosion in ITER due to the very low target electron temperature.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [1]; ORCiD logo [4]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [5]; ORCiD logo [1]; ORCiD logo [1]
  1. General Atomics, San Diego, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of California, San Diego, CA (United States)
  4. Univ. of Wisconsin, Madison, WI (United States)
  5. Univ. of Toronto, ON (Canada)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); U.S. Dept. of Energy (USDOE), Washington DC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1561609
Alternate Identifier(s):
OSTI ID: 1525522; OSTI ID: 1569625
Grant/Contract Number:  
[AC05-00OR22725; FC02-04ER54698; FG02-07ER54917; SC0013911; AC04-94AL8500; AC05-06OR23100]
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
[ Journal Volume: 26; Journal Issue: 6; Conference: 60. Annual Meeting of the APS Division of Plasma Physics, Portland, OR (United States), 5-9 Nov 2018]; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Abrams, Tyler, Unterberg, Ezekial A., Rudakov, D. L., Leonard, A. W., Schmitz, Oliver, Shiraki, Daisuke, Baylor, Larry R., Stangeby, Peter C., Thomas, D. M., and Wang, H. Q. Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER. United States: N. p., 2019. Web. doi:10.1063/1.5089895.
Abrams, Tyler, Unterberg, Ezekial A., Rudakov, D. L., Leonard, A. W., Schmitz, Oliver, Shiraki, Daisuke, Baylor, Larry R., Stangeby, Peter C., Thomas, D. M., & Wang, H. Q. Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER. United States. doi:10.1063/1.5089895.
Abrams, Tyler, Unterberg, Ezekial A., Rudakov, D. L., Leonard, A. W., Schmitz, Oliver, Shiraki, Daisuke, Baylor, Larry R., Stangeby, Peter C., Thomas, D. M., and Wang, H. Q. Mon . "Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER". United States. doi:10.1063/1.5089895.
@article{osti_1561609,
title = {Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER},
author = {Abrams, Tyler and Unterberg, Ezekial A. and Rudakov, D. L. and Leonard, A. W. and Schmitz, Oliver and Shiraki, Daisuke and Baylor, Larry R. and Stangeby, Peter C. and Thomas, D. M. and Wang, H. Q.},
abstractNote = {The free-streaming plus recycling model (FSRM) has recently been developed to understand and predict tungsten gross erosion rates from the divertor during edge localized modes (ELMs). In this work, the FSRM was tested against the experimental measurements of W sputtering during ELMs, conducted via fast neutral tungsten (WI) spectroscopy. Good agreement is observed using a variety of controlling techniques, including gas puffing, neutral beam heating, and plasma shaping to modify the pedestal stability boundary and, thus, the ELM behavior. ELM mitigation by pellet pacing was observed to strongly reduce W sputtering by flushing C impurities from the pedestal and reducing the divertor target electron temperature. No reduction of W sputtering was observed during the application of resonant magnetic perturbations (RMPs), in contrast to the prediction of the FSRM. Potential sources of this discrepancy are discussed. Lastly, the framework of the FSRM is utilized to predict intra-ELM W sputtering rates in ITER. It is concluded that W erosion during ELMs in ITER will be caused mainly by free-streaming fuel ions, but free-streaming seeded impurities (N or Ne) may increase the erosion rate significantly if present in the pedestal at even the 1% level. Impurity recycling is not expected to cause critical W erosion in ITER due to the very low target electron temperature.},
doi = {10.1063/1.5089895},
journal = {Physics of Plasmas},
number = [6],
volume = [26],
place = {United States},
year = {2019},
month = {6}
}

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