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Title: Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths

Abstract

The heat flux distributions on divertor targets in H-mode plasmas are grave concerns for future devices. We seek to simulate the tokamak boundary plasma turbulence and heat transport in the edge localized mode-suppressed regimes. The improved BOUT++ model shows that not only I p but also the radial electric field E r plays a crucial role on the turbulence behavior and sets the heat flux width. Instead of calculating E r from the pressure gradient term (diamagnetic E r), it is measured from the plasma transport equations with the sheath potential in the scrape-off layer and the plasma density and temperature profiles inside the separatrix from the experiment. The simulation results with the new E r model have better agreement with the experiment than using the diamagnetic Er model: (1) The electromagnetic turbulence in enhanced D α H-mode shows the characteristics of quasi-coherent modes (QCMs) and broadband turbulence. The mode spectra are in agreement with the phase contrast imaging data and almost has no change in comparison to the cases which use the diamagnetic Er model; (2) the self-consistent boundary E r is needed for the turbulence simulations to get the consistent heat flux width with the experiment; (3) themore » frequencies of the QCMs are proportional to E r, while the divertor heat flux widths are inversely proportional to Er; and (4) the BOUT++ turbulence simulations yield a similar heat flux width to the experimental Eich scaling law and the prediction from the Goldston heuristic drift model.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [3];  [4];  [5];  [5];  [5]; ORCiD logo [5]; ORCiD logo [5];  [6];  [6]
  1. Univ. of Science and Technology of China, Hefei (China); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chinese Academy of Sciences (CAS), Hefei (China)
  4. Dalian Univ. of Technology (China)
  5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  6. Univ. of Science and Technology of China, Hefei (China)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Natural Science Foundation of China (NNSFC); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1543851
Alternate Identifier(s):
OSTI ID: 1436555; OSTI ID: 1566016
Report Number(s):
LLNL-JRNL-742019
Journal ID: ISSN 1070-664X
Grant/Contract Number:  
FC02-99ER54512; SC0014264; AC52-7NA27344; AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 5; 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

Chen, B., Xu, X. Q., Xia, T. Y., Li, N. M., Porkolab, M., Edlund, E., LaBombard, B., Terry, J., Hughes, J. W., Ye, M. Y., and Wan, Y. X. Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths. United States: N. p., 2018. Web. doi:10.1063/1.5016582.
Chen, B., Xu, X. Q., Xia, T. Y., Li, N. M., Porkolab, M., Edlund, E., LaBombard, B., Terry, J., Hughes, J. W., Ye, M. Y., & Wan, Y. X. Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths. United States. doi:10.1063/1.5016582.
Chen, B., Xu, X. Q., Xia, T. Y., Li, N. M., Porkolab, M., Edlund, E., LaBombard, B., Terry, J., Hughes, J. W., Ye, M. Y., and Wan, Y. X. Wed . "Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths". United States. doi:10.1063/1.5016582. https://www.osti.gov/servlets/purl/1543851.
@article{osti_1543851,
title = {Progress towards modeling tokamak boundary plasma turbulence and understanding its role in setting divertor heat flux widths},
author = {Chen, B. and Xu, X. Q. and Xia, T. Y. and Li, N. M. and Porkolab, M. and Edlund, E. and LaBombard, B. and Terry, J. and Hughes, J. W. and Ye, M. Y. and Wan, Y. X.},
abstractNote = {The heat flux distributions on divertor targets in H-mode plasmas are grave concerns for future devices. We seek to simulate the tokamak boundary plasma turbulence and heat transport in the edge localized mode-suppressed regimes. The improved BOUT++ model shows that not only Ip but also the radial electric field Er plays a crucial role on the turbulence behavior and sets the heat flux width. Instead of calculating Er from the pressure gradient term (diamagnetic Er), it is measured from the plasma transport equations with the sheath potential in the scrape-off layer and the plasma density and temperature profiles inside the separatrix from the experiment. The simulation results with the new Er model have better agreement with the experiment than using the diamagnetic Er model: (1) The electromagnetic turbulence in enhanced Dα H-mode shows the characteristics of quasi-coherent modes (QCMs) and broadband turbulence. The mode spectra are in agreement with the phase contrast imaging data and almost has no change in comparison to the cases which use the diamagnetic Er model; (2) the self-consistent boundary Er is needed for the turbulence simulations to get the consistent heat flux width with the experiment; (3) the frequencies of the QCMs are proportional to Er, while the divertor heat flux widths are inversely proportional to Er; and (4) the BOUT++ turbulence simulations yield a similar heat flux width to the experimental Eich scaling law and the prediction from the Goldston heuristic drift model.},
doi = {10.1063/1.5016582},
journal = {Physics of Plasmas},
number = 5,
volume = 25,
place = {United States},
year = {2018},
month = {5}
}

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