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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 H-mode 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 (B_T0 = 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 (beta_N/beta_N-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 (kappa > 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

Creator(s)/Author(s):
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Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
U. S. Department of Energy
Keywords:
Scenario development; Real-time control; NSTX-U; Spherical tokamak; Wall conditioning; Tokamak startup; Error field correction; L-mode; H-mode
OSTI Identifier:
1562052
DOI:
10.11578/1562052

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, Jaworski, M A, Kaye, S M, LeBlanc, B P, Ono, M, Park, J -K, Podesta, M, Raman, R, and Soukhanovskii, V A. Scenario Development During Commissioning Operations on the National Spherical Torus Experiment Upgrade. United States: N. p., 2018. Web. doi:10.11578/1562052.
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, Jaworski, M A, Kaye, S M, LeBlanc, B P, Ono, M, Park, J -K, Podesta, M, Raman, R, & Soukhanovskii, V A. Scenario Development During Commissioning Operations on the National Spherical Torus Experiment Upgrade. United States. doi:10.11578/1562052.
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, Jaworski, M A, Kaye, S M, LeBlanc, B P, Ono, M, Park, J -K, Podesta, M, Raman, R, and Soukhanovskii, V A. 2018. "Scenario Development During Commissioning Operations on the National Spherical Torus Experiment Upgrade". United States. doi:10.11578/1562052. https://www.osti.gov/servlets/purl/1562052. Pub date:Sun Apr 01 00:00:00 EDT 2018
@article{osti_1562052,
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 Jaworski, M A and Kaye, S M and LeBlanc, B P and Ono, M and Park, J -K and Podesta, M and Raman, R and Soukhanovskii, V A},
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 H-mode 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 (B_T0 = 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 (beta_N/beta_N-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 (kappa > 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 = {10.11578/1562052},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {4}
}

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