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Title: H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D

Abstract

Plasmas with a negative triangularity shape have been created on the DIII-D tokamak that, despite maintaining standard L-mode edge radial profiles, reach volume averaged pressure levels typical of H-mode scenarios. Within the auxiliary power available for these experiments, plasmas exhibit near-zero power degradation while sustaining βN = 2.7 and H 98,y2 = 1.2 for several energy confinement times. Detailed comparison with matched discharges at positive triangularity indicates that Trapped Electron Modes are weakened at negative triangularity, consistent with increased confinement and reduced intensity of fluctuations in electron density, electron temperature, and ion density. Furthermore, these results indicate that a negative triangularity plasma operating without an edge pedestal might provide an attractive scenario for operations in future reactors.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3];  [3]; ORCiD logo [3]; ORCiD logo [3];  [4];  [5];  [1]; ORCiD logo [3];  [1]; ORCiD logo [1]; ORCiD logo [6]; ORCiD logo [3]; ORCiD logo [3];  [7]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [7]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Univ. of Texas at Austin, Austin, TX (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Univ. of Wisconsin at Madison, Madison, WI (United States)
  6. Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)
  7. Univ. of California at Los Angeles, Los Angeles, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
DIII-D Team
OSTI Identifier:
1569039
Alternate Identifier(s):
OSTI ID: 1508885; OSTI ID: 1545365
Grant/Contract Number:  
AC52-07NA27344; SC0016154; FC02-04ER54698; FC02-99ER54512; FG02-94ER54235
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 4; 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; Triangularity; ELMs; Reactor; TEM; Stability

Citation Formats

Marinoni, A., Austin, M. E., Hyatt, A. W., Walker, M. L., Candy, J., Chrystal, C., Lasnier, C. J., McKee, G. R., Odstrčil, T., Petty, C. C., Porkolab, M., Rost, J. C., Sauter, O., Smith, S. P., Staebler, G. M., Sung, C., Thome, K. E., Turnbull, A. D., and Zeng, L. H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D. United States: N. p., 2019. Web. doi:10.1063/1.5091802.
Marinoni, A., Austin, M. E., Hyatt, A. W., Walker, M. L., Candy, J., Chrystal, C., Lasnier, C. J., McKee, G. R., Odstrčil, T., Petty, C. C., Porkolab, M., Rost, J. C., Sauter, O., Smith, S. P., Staebler, G. M., Sung, C., Thome, K. E., Turnbull, A. D., & Zeng, L. H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D. United States. doi:10.1063/1.5091802.
Marinoni, A., Austin, M. E., Hyatt, A. W., Walker, M. L., Candy, J., Chrystal, C., Lasnier, C. J., McKee, G. R., Odstrčil, T., Petty, C. C., Porkolab, M., Rost, J. C., Sauter, O., Smith, S. P., Staebler, G. M., Sung, C., Thome, K. E., Turnbull, A. D., and Zeng, L. Thu . "H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D". United States. doi:10.1063/1.5091802.
@article{osti_1569039,
title = {H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D},
author = {Marinoni, A. and Austin, M. E. and Hyatt, A. W. and Walker, M. L. and Candy, J. and Chrystal, C. and Lasnier, C. J. and McKee, G. R. and Odstrčil, T. and Petty, C. C. and Porkolab, M. and Rost, J. C. and Sauter, O. and Smith, S. P. and Staebler, G. M. and Sung, C. and Thome, K. E. and Turnbull, A. D. and Zeng, L.},
abstractNote = {Plasmas with a negative triangularity shape have been created on the DIII-D tokamak that, despite maintaining standard L-mode edge radial profiles, reach volume averaged pressure levels typical of H-mode scenarios. Within the auxiliary power available for these experiments, plasmas exhibit near-zero power degradation while sustaining βN = 2.7 and H98,y2 = 1.2 for several energy confinement times. Detailed comparison with matched discharges at positive triangularity indicates that Trapped Electron Modes are weakened at negative triangularity, consistent with increased confinement and reduced intensity of fluctuations in electron density, electron temperature, and ion density. Furthermore, these results indicate that a negative triangularity plasma operating without an edge pedestal might provide an attractive scenario for operations in future reactors.},
doi = {10.1063/1.5091802},
journal = {Physics of Plasmas},
number = 4,
volume = 26,
place = {United States},
year = {2019},
month = {4}
}

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