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Title: Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U

Abstract

Here, the upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgraded to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]; ORCiD logo [2];  [1];  [2];  [1];  [1];  [2];  [3]; ORCiD logo [1]; ORCiD logo [1];  [4];  [5];  [3]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Univ., Princeton, NJ (United States)
  4. Columbia Univ., New York, NY (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1419785
Report Number(s):
PPPL-5441
Journal ID: ISSN 0029-5515; TRN: US1801392
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 3; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; spherical torus; plasma boundary control; plasma boundary reconstruction; MIMO feedback control

Citation Formats

Boyer, M. D., Battaglia, D. J., Mueller, D., Eidietis, N., Erickson, K., Ferron, J., Gates, D. A., Gerhardt, S., Johnson, R., Kolemen, E., Menard, J., Myers, C. E., Sabbagh, S. A., Scotti, F., and Vail, P. Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aaa4d0.
Boyer, M. D., Battaglia, D. J., Mueller, D., Eidietis, N., Erickson, K., Ferron, J., Gates, D. A., Gerhardt, S., Johnson, R., Kolemen, E., Menard, J., Myers, C. E., Sabbagh, S. A., Scotti, F., & Vail, P. Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U. United States. https://doi.org/10.1088/1741-4326/aaa4d0
Boyer, M. D., Battaglia, D. J., Mueller, D., Eidietis, N., Erickson, K., Ferron, J., Gates, D. A., Gerhardt, S., Johnson, R., Kolemen, E., Menard, J., Myers, C. E., Sabbagh, S. A., Scotti, F., and Vail, P. Thu . "Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U". United States. https://doi.org/10.1088/1741-4326/aaa4d0. https://www.osti.gov/servlets/purl/1419785.
@article{osti_1419785,
title = {Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U},
author = {Boyer, M. D. and Battaglia, D. J. and Mueller, D. and Eidietis, N. and Erickson, K. and Ferron, J. and Gates, D. A. and Gerhardt, S. and Johnson, R. and Kolemen, E. and Menard, J. and Myers, C. E. and Sabbagh, S. A. and Scotti, F. and Vail, P.},
abstractNote = {Here, the upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgraded to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.},
doi = {10.1088/1741-4326/aaa4d0},
url = {https://www.osti.gov/biblio/1419785}, journal = {Nuclear Fusion},
issn = {0029-5515},
number = 3,
volume = 58,
place = {United States},
year = {2018},
month = {1}
}

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    A scalable real-time framework for Thomson scattering analysis: Application to NSTX-U
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    Design and simulation of the snowflake divertor control for NSTX–U
    journal, January 2019


    Initial development of the DIII–D snowflake divertor control
    journal, April 2018


    Effect of sawtooth crashes on fast ion distribution in NSTX-U
    journal, July 2018


    Divertor leg filaments in NSTX-U
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