Scenario Development During Commissioning Operations on the National Spherical Torus Experiment Upgrade

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

doi:10.11578/1562052

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 »« less

Publication Date:: 2018-04-01

DOE Contract Number:: AC02-09CH11466

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:: https://doi.org/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.

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                    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:https://doi.org/10.11578/1562052

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                    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:https://doi.org/10.11578/1562052.  https://www.osti.gov/servlets/purl/1562052. Pub date:Sun Apr 01 00:00:00 EDT 2018

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@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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