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Title: Snowflake divertor experiments in the DIII-D, NSTX, and NSTX-U tokamaks aimed at the development of the divertor power exhaust solution

Abstract

Experimental results from the National Spherical Torus Experiment (NSTX), a medium-size spherical tokamak with a compact divertor, and DIII-D, a large conventional aspect ratio tokamak, demonstrate that the snowflake (SF) divertor configuration may provide a promising solution for mitigating divertor heat loads and target plate erosion compatible with core H-mode confinement in the future fusion devices, where the standard radiative divertor solution may be inadequate. In NSTX, where the initial high-power SF experiment was performed, the SF divertor was compatible with H-mode confinement, and led to the destabilization of large Edge Localized Modes (ELMs). However, a stable partial detachment of the outer strike point was also achieved where inter-ELM peak heat flux was reduced by factors 3-5, and peak ELM heat flux was reduced by up to 80% (see standard divertor). The DIII-D studies show the SF divertor enables significant power spreading in attached and radiative divertor conditions. Results include: compatibility with the core and pedestal, peak inter-ELM divertor heat flux reduction due to geometry at lower ne, and ELM energy and divertor peak heat flux reduction, especially prominent in radiative D2-seeded SF divertor, and nearly complete power detachment and broader radiated power distribution in the radiative D2-seeded SF divertormore » at PSOL = 3 - 4 MW. A variety of SF configurations can be supported by the divertor coil set in NSTX Upgrade. Edge transport modeling with the multifluid edge transport code UEDGE shows that the radiative SF divertor can successfully reduce peak divertor heat flux for the projected PSOL ≃ 9 MW case. Furthermore, the radiative SF divertor with carbon impurity provides a wider ne operating window, 50% less argon is needed in the impurity-seeded SF configuration to achieve similar qpeak reduction factors (see standard divertor).« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [2];  [1];  [1];  [1];  [1];  [3];  [3];  [3];  [3];  [3];  [3];  [3];  [3];  [3] more »;  [3];  [3];  [4];  [4];  [4];  [4];  [4];  [5];  [6];  [7] « less
+ Show Author Affiliations
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); College of William and Mary, Williamsburg, VA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. General Atomics, San Diego, CA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Univ. of Washington, Seattle, WA (United States)
  7. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1343020
Report Number(s):
LLNL-JRNL-675395
Journal ID: ISSN 0093-3813; TRN: US1701246
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Plasma Science
Additional Journal Information:
Journal Volume: 44; Journal Issue: 12; Journal ID: ISSN 0093-3813
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; tokamaks; divertors; plasma materials interactions

Citation Formats

Soukhanovskii, V. A., Allen, S. L., Fenstermacher, M. E., Lasnier, C. J., Makowski, M. A., McLean, A. G., Meier, E. T., Meyer, W. H., Rognlien, T. D., Ryutov, D. D., Scotti, F., Kolemen, E., Bell, R. E., Diallo, A., Gerhardt, S., Kaita, R., Kaye, S., LeBlanc, B. P., Maingi, R., Menard, J. E., Podesta, M., Roquemore, A. L., Groebner, R. J., Hyatt, A. W., Leonard, A. W., Osborne, T. H., Petrie, T. W., Ahn, J. -W., Raman, R., and Watkins, J. G. Snowflake divertor experiments in the DIII-D, NSTX, and NSTX-U tokamaks aimed at the development of the divertor power exhaust solution. United States: N. p., 2016. Web. doi:10.1109/TPS.2016.2625325.
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Soukhanovskii, V. A., Allen, S. L., Fenstermacher, M. E., Lasnier, C. J., Makowski, M. A., McLean, A. G., Meier, E. T., Meyer, W. H., Rognlien, T. D., Ryutov, D. D., Scotti, F., Kolemen, E., Bell, R. E., Diallo, A., Gerhardt, S., Kaita, R., Kaye, S., LeBlanc, B. P., Maingi, R., Menard, J. E., Podesta, M., Roquemore, A. L., Groebner, R. J., Hyatt, A. W., Leonard, A. W., Osborne, T. H., Petrie, T. W., Ahn, J. -W., Raman, R., & Watkins, J. G. Snowflake divertor experiments in the DIII-D, NSTX, and NSTX-U tokamaks aimed at the development of the divertor power exhaust solution. United States. https://doi.org/10.1109/TPS.2016.2625325
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Soukhanovskii, V. A., Allen, S. L., Fenstermacher, M. E., Lasnier, C. J., Makowski, M. A., McLean, A. G., Meier, E. T., Meyer, W. H., Rognlien, T. D., Ryutov, D. D., Scotti, F., Kolemen, E., Bell, R. E., Diallo, A., Gerhardt, S., Kaita, R., Kaye, S., LeBlanc, B. P., Maingi, R., Menard, J. E., Podesta, M., Roquemore, A. L., Groebner, R. J., Hyatt, A. W., Leonard, A. W., Osborne, T. H., Petrie, T. W., Ahn, J. -W., Raman, R., and Watkins, J. G. Wed . "Snowflake divertor experiments in the DIII-D, NSTX, and NSTX-U tokamaks aimed at the development of the divertor power exhaust solution". United States. https://doi.org/10.1109/TPS.2016.2625325. https://www.osti.gov/servlets/purl/1343020.
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@article{osti_1343020,
title = {Snowflake divertor experiments in the DIII-D, NSTX, and NSTX-U tokamaks aimed at the development of the divertor power exhaust solution},
author = {Soukhanovskii, V. A. and Allen, S. L. and Fenstermacher, M. E. and Lasnier, C. J. and Makowski, M. A. and McLean, A. G. and Meier, E. T. and Meyer, W. H. and Rognlien, T. D. and Ryutov, D. D. and Scotti, F. and Kolemen, E. and Bell, R. E. and Diallo, A. and Gerhardt, S. and Kaita, R. and Kaye, S. and LeBlanc, B. P. and Maingi, R. and Menard, J. E. and Podesta, M. and Roquemore, A. L. and Groebner, R. J. and Hyatt, A. W. and Leonard, A. W. and Osborne, T. H. and Petrie, T. W. and Ahn, J. -W. and Raman, R. and Watkins, J. G.},
abstractNote = {Experimental results from the National Spherical Torus Experiment (NSTX), a medium-size spherical tokamak with a compact divertor, and DIII-D, a large conventional aspect ratio tokamak, demonstrate that the snowflake (SF) divertor configuration may provide a promising solution for mitigating divertor heat loads and target plate erosion compatible with core H-mode confinement in the future fusion devices, where the standard radiative divertor solution may be inadequate. In NSTX, where the initial high-power SF experiment was performed, the SF divertor was compatible with H-mode confinement, and led to the destabilization of large Edge Localized Modes (ELMs). However, a stable partial detachment of the outer strike point was also achieved where inter-ELM peak heat flux was reduced by factors 3-5, and peak ELM heat flux was reduced by up to 80% (see standard divertor). The DIII-D studies show the SF divertor enables significant power spreading in attached and radiative divertor conditions. Results include: compatibility with the core and pedestal, peak inter-ELM divertor heat flux reduction due to geometry at lower ne, and ELM energy and divertor peak heat flux reduction, especially prominent in radiative D2-seeded SF divertor, and nearly complete power detachment and broader radiated power distribution in the radiative D2-seeded SF divertor at PSOL = 3 - 4 MW. A variety of SF configurations can be supported by the divertor coil set in NSTX Upgrade. Edge transport modeling with the multifluid edge transport code UEDGE shows that the radiative SF divertor can successfully reduce peak divertor heat flux for the projected PSOL ≃ 9 MW case. Furthermore, the radiative SF divertor with carbon impurity provides a wider ne operating window, 50% less argon is needed in the impurity-seeded SF configuration to achieve similar qpeak reduction factors (see standard divertor).},
doi = {10.1109/TPS.2016.2625325},
journal = {IEEE Transactions on Plasma Science},
number = 12,
volume = 44,
place = {United States},
year = {Wed Nov 16 00:00:00 EST 2016},
month = {Wed Nov 16 00:00:00 EST 2016}
}
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https://doi.org/10.1109/TPS.2016.2625325
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Works referencing / citing this record:

A review of radiative detachment studies in tokamak advanced magnetic divertor configurations
journal, April 2017

Design and simulation of the snowflake divertor control for NSTX–U
journal, January 2019

  • Vail, P. J.; Boyer, M. D.; Welander, A. S.
  • Plasma Physics and Controlled Fusion, Vol. 61, Issue 3
  • DOI: 10.1088/1361-6587/aaf94a

Developing physics basis for the snowflake divertor in the DIII-D tokamak
journal, February 2018

  • Soukhanovskii, V. A.; Allen, S. L.; Fenstermacher, M. E.
  • Nuclear Fusion, Vol. 58, Issue 3
  • DOI: 10.1088/1741-4326/aaa6de

Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade
journal, February 2018

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