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Title: Impact of a large density gradient on linear and nonlinear edge-localized mode simulations

Abstract

Here, the impact of a large density gradient on edge-localized modes (ELMs) is studied linearly and nonlinearly by employing both two-fluid and gyro-fluid simulations. In two-fluid simulations, the ion diamagnetic stabilization on high-n modes disappears when the large density gradient is taken into account. But gyro-fluid simulations show that the finite Larmor radius (FLR) effect can effectively stabilize high-n modes, so the ion diamagnetic effect alone is not sufficient to represent the FLR stabilizing effect. We further demonstrate that additional gyroviscous terms must be kept in the two-fluid model to recover the linear results from the gyro-fluid model. Nonlinear simulations show that the density variation significantly weakens the E × B shearing at the top of the pedestal and thus leads to more energy loss during ELMs. The turbulence spectrum after an ELM crash is measured and has the relation of $$P(k_{z})\propto k_{z}^{-3.3}$$ .

Authors:
 [1];  [2];  [3];  [2];  [4]
  1. Peking Univ., Beijing (People's Republic of China); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Chinese Academy of Sciences, Hefei (People's Republic of China)
  4. National Fusion Research Institute, Daejeon (Republic of Korea)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1357326
Report Number(s):
LLNL-JRNL-630194
Journal ID: ISSN 0029-5515
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 53; Journal Issue: 11; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION

Citation Formats

Xi, P. W., Xu, X. Q., Xia, T. Y., Nevins, W. M., and Kim, S. S. Impact of a large density gradient on linear and nonlinear edge-localized mode simulations. United States: N. p., 2013. Web. doi:10.1088/0029-5515/53/11/113020.
Xi, P. W., Xu, X. Q., Xia, T. Y., Nevins, W. M., & Kim, S. S. Impact of a large density gradient on linear and nonlinear edge-localized mode simulations. United States. doi:10.1088/0029-5515/53/11/113020.
Xi, P. W., Xu, X. Q., Xia, T. Y., Nevins, W. M., and Kim, S. S. Fri . "Impact of a large density gradient on linear and nonlinear edge-localized mode simulations". United States. doi:10.1088/0029-5515/53/11/113020. https://www.osti.gov/servlets/purl/1357326.
@article{osti_1357326,
title = {Impact of a large density gradient on linear and nonlinear edge-localized mode simulations},
author = {Xi, P. W. and Xu, X. Q. and Xia, T. Y. and Nevins, W. M. and Kim, S. S.},
abstractNote = {Here, the impact of a large density gradient on edge-localized modes (ELMs) is studied linearly and nonlinearly by employing both two-fluid and gyro-fluid simulations. In two-fluid simulations, the ion diamagnetic stabilization on high-n modes disappears when the large density gradient is taken into account. But gyro-fluid simulations show that the finite Larmor radius (FLR) effect can effectively stabilize high-n modes, so the ion diamagnetic effect alone is not sufficient to represent the FLR stabilizing effect. We further demonstrate that additional gyroviscous terms must be kept in the two-fluid model to recover the linear results from the gyro-fluid model. Nonlinear simulations show that the density variation significantly weakens the E × B shearing at the top of the pedestal and thus leads to more energy loss during ELMs. The turbulence spectrum after an ELM crash is measured and has the relation of $P(k_{z})\propto k_{z}^{-3.3}$ .},
doi = {10.1088/0029-5515/53/11/113020},
journal = {Nuclear Fusion},
number = 11,
volume = 53,
place = {United States},
year = {2013},
month = {9}
}

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