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Title: Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade

Abstract

The National Spherical Torus Experiment Upgrade (NSTX-U) will advance the physics basis required for achieving steady-state, high-beta, and high-confinement conditions in a tokamak by accessing high toroidal field (1 T) and plasma current (1.0 - 2.0 MA) in a low aspect ratio geometry (A = 1.6 - 1.8) with flexible auxiliary heating systems (12 MW NBI, 6 MW HHFW). This paper describes progress in the development of L- and Hmode discharge scenarios and the commissioning of operational tools in the first ten weeks of operation that enable the scientific mission of NSTX-U. Vacuum field calculations completed prior to operations supported the rapid development and optimization of inductive breakdown at different values of ohmic solenoid current. The toroidal magnetic field (BT0 = 0.65 T) exceeded the maximum values achieved on NSTX and novel long-pulse L-mode discharges with regular sawtooth activity exceeded the longest pulses produced on NSTX (tpulse > 1.8s). The increased flux of the central solenoid facilitated the development of stationary L-mode discharges over a range of density and plasma current (Ip). H-mode discharges achieved similar levels of stored energy, confinement (H98y,2 > 1) and stability (βN/βN-nowall > 1) compared to NSTX discharges for Ip ≤ 1 MA. High-performance H-modemore » scenarios require an L-H transition early in the Ip ramp-up phase in order to obtain low internal inductance (li) throughout the discharge, which is conducive to maintaining vertical stability at high elongation (κ > 2.2) and achieving long periods of MHD quiescent operations. The rapid progress in developing L- and H-mode scenarios in support of the scientific program was enabled by advances in real-time plasma control, efficient error field identification and correction, effective conditioning of the graphite wall and excellent diagnostic availability.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [2];  [3];  [4];  [1];  [2];  [1];  [1];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1] more »;  [5];  [3] « less
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Columbia Univ., New York, NY (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Univ. of Illinois, Urbana-Champaign, IL (United States)
  5. Univ. of Washington, Seattle, WA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
the NSTX-U Research, Operations and Engineering Team
OSTI Identifier:
1425032
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 4; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Battaglia, D. J., Boyer, M. D., Gerhardt, S., Mueller, D., Myers, C. E., Guttenfelder, W., Menard, J. E., Sabbagh, S. A., Scotti, F., Bedoya, F., Bell, R. E., Berkery, J. W., Diallo, A., Ferraro, N., Kaye, S. M., Jaworski, M. A., LeBlanc, B. P., Ono, M., Park, J. -K., Podesta, M., Raman, R., and Soukhanovskii, V.. Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aaa6e0.
Battaglia, D. J., Boyer, M. D., Gerhardt, S., Mueller, D., Myers, C. E., Guttenfelder, W., Menard, J. E., Sabbagh, S. A., Scotti, F., Bedoya, F., Bell, R. E., Berkery, J. W., Diallo, A., Ferraro, N., Kaye, S. M., Jaworski, M. A., LeBlanc, B. P., Ono, M., Park, J. -K., Podesta, M., Raman, R., & Soukhanovskii, V.. Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade. United States. doi:10.1088/1741-4326/aaa6e0.
Battaglia, D. J., Boyer, M. D., Gerhardt, S., Mueller, D., Myers, C. E., Guttenfelder, W., Menard, J. E., Sabbagh, S. A., Scotti, F., Bedoya, F., Bell, R. E., Berkery, J. W., Diallo, A., Ferraro, N., Kaye, S. M., Jaworski, M. A., LeBlanc, B. P., Ono, M., Park, J. -K., Podesta, M., Raman, R., and Soukhanovskii, V.. Tue . "Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade". United States. doi:10.1088/1741-4326/aaa6e0.
@article{osti_1425032,
title = {Scenario development during commissioning operations on the National Spherical Torus Experiment Upgrade},
author = {Battaglia, D. J. and Boyer, M. D. and Gerhardt, S. and Mueller, D. and Myers, C. E. and Guttenfelder, W. and Menard, J. E. and Sabbagh, S. A. and Scotti, F. and Bedoya, F. and Bell, R. E. and Berkery, J. W. and Diallo, A. and Ferraro, N. and Kaye, S. M. and Jaworski, M. A. and LeBlanc, B. P. and Ono, M. and Park, J. -K. and Podesta, M. and Raman, R. and Soukhanovskii, V.},
abstractNote = {The National Spherical Torus Experiment Upgrade (NSTX-U) will advance the physics basis required for achieving steady-state, high-beta, and high-confinement conditions in a tokamak by accessing high toroidal field (1 T) and plasma current (1.0 - 2.0 MA) in a low aspect ratio geometry (A = 1.6 - 1.8) with flexible auxiliary heating systems (12 MW NBI, 6 MW HHFW). This paper describes progress in the development of L- and Hmode discharge scenarios and the commissioning of operational tools in the first ten weeks of operation that enable the scientific mission of NSTX-U. Vacuum field calculations completed prior to operations supported the rapid development and optimization of inductive breakdown at different values of ohmic solenoid current. The toroidal magnetic field (BT0 = 0.65 T) exceeded the maximum values achieved on NSTX and novel long-pulse L-mode discharges with regular sawtooth activity exceeded the longest pulses produced on NSTX (tpulse > 1.8s). The increased flux of the central solenoid facilitated the development of stationary L-mode discharges over a range of density and plasma current (Ip). H-mode discharges achieved similar levels of stored energy, confinement (H98y,2 > 1) and stability (βN/βN-nowall > 1) compared to NSTX discharges for Ip ≤ 1 MA. High-performance H-mode scenarios require an L-H transition early in the Ip ramp-up phase in order to obtain low internal inductance (li) throughout the discharge, which is conducive to maintaining vertical stability at high elongation (κ > 2.2) and achieving long periods of MHD quiescent operations. The rapid progress in developing L- and H-mode scenarios in support of the scientific program was enabled by advances in real-time plasma control, efficient error field identification and correction, effective conditioning of the graphite wall and excellent diagnostic availability.},
doi = {10.1088/1741-4326/aaa6e0},
journal = {Nuclear Fusion},
number = 4,
volume = 58,
place = {United States},
year = {Tue Feb 20 00:00:00 EST 2018},
month = {Tue Feb 20 00:00:00 EST 2018}
}

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