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Title: Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix

Abstract

We show for JET and ASDEX Upgrade, based on Thomson-scattering measurements, a clear correlation of the density limit of the tokamak H-Mode highcon nement regime with the approach to the ideal ballooning instability threshold at the periphery of the plasma. It is shown that the MHD ballooning parameter at the separatrix position αsep increases about linearly with the separatrix density normalized to Greenwald density, n e,sep=n GW for a wide range of discharge parameters in both devices. The observed operational space is found to reach at maximum n e,sep=nGW ≈ 0.4-0.5 at values for α sep ≈ 2-2.5, in the range of theoretical predictions for ballooning instability. This work supports the hypothesis that the H-Mode density limit may be set by ballooning stability at the separatrix.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1];  [1];  [1]
  1. Max Planck Inst. for Plasma Physics, Garching (Germany)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
ASDEX Upgrade Team; JET Contributors
OSTI Identifier:
1473625
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 3; Related Information: This work has been carried out within the framework of the EUROfusion Consortiumand has received funding from the Euratom research and training programme 2014-2018under grant agreement No 633053. The views and opinions expressed herein do notnecessarily reflect those of the European Commission. The work of RJG was supportedby US DOE Contract No. DE-AC02-09CH11466; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Eich, T., Goldston, R. J., Kallenbach, A., Sieglin, B., and Sun, H. J. Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aaa340.
Eich, T., Goldston, R. J., Kallenbach, A., Sieglin, B., & Sun, H. J. Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix. United States. doi:10.1088/1741-4326/aaa340.
Eich, T., Goldston, R. J., Kallenbach, A., Sieglin, B., and Sun, H. J. Mon . "Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix". United States. doi:10.1088/1741-4326/aaa340. https://www.osti.gov/servlets/purl/1473625.
@article{osti_1473625,
title = {Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix},
author = {Eich, T. and Goldston, R. J. and Kallenbach, A. and Sieglin, B. and Sun, H. J.},
abstractNote = {We show for JET and ASDEX Upgrade, based on Thomson-scattering measurements, a clear correlation of the density limit of the tokamak H-Mode highcon nement regime with the approach to the ideal ballooning instability threshold at the periphery of the plasma. It is shown that the MHD ballooning parameter at the separatrix position αsep increases about linearly with the separatrix density normalized to Greenwald density, ne,sep=nGW for a wide range of discharge parameters in both devices. The observed operational space is found to reach at maximum ne,sep=nGW ≈ 0.4-0.5 at values for αsep ≈ 2-2.5, in the range of theoretical predictions for ballooning instability. This work supports the hypothesis that the H-Mode density limit may be set by ballooning stability at the separatrix.},
doi = {10.1088/1741-4326/aaa340},
journal = {Nuclear Fusion},
issn = {0029-5515},
number = 3,
volume = 58,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
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Cited by: 7 works
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Figures / Tables:

Table 1. Table 1.: Discharge parameters of analysed plasmas.

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.