Stability of DIII-D high-performance, negative central shear discharges

Hanson, Jeremy M.; Berkery, John W.; Bialek, James M.; Clement, Mitchell; Ferron, John R.; Garafalo, Andrea M.; Holcomb, Christopher T.; La Haye, Robert J.; Lanctot, Matthew J.; Luce, Timothy C.; Navratil, Gerald A.; Olofsson, K. Erik J.; Strait, Edward J.; Turco, Francesca; Turnbull, Alan D.

doi:10.1088/1741-4326/aa6266

Stability of DIII-D high-performance, negative central shear discharges

Journal Article · Mon Mar 20 00:00:00 EDT 2017 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aa6266· OSTI ID:1354791

Hanson, Jeremy M. ^[1]; Berkery, John W. ^[2]; Bialek, James M. ^[2]; Clement, Mitchell ^[3]; Ferron, John R. ^[4]; Garafalo, Andrea M. ^[4]; Holcomb, Christopher T. ^[5]; La Haye, Robert J. ^[4]; Lanctot, Matthew J. ^[4]; Luce, Timothy C. ^[4]; Navratil, Gerald A. ^[2]; Olofsson, K. Erik J. ^[6]; Strait, Edward J. ^[4]; Turco, Francesca ^[2]; Turnbull, Alan D. ^[4]

Columbia Univ., New York, NY (United States); General Atomics
Columbia Univ., New York, NY (United States)
Columbia Univ., New York, NY (United States); Univ. of California San Diego, La Jolla, CA (United States)
General Atomics, San Diego, CA (United States)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
ORAU Oak Ridge Associated Univ., Oak Ridge, TN (United States)

Tokamak plasma experiments on the DIII-D device demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor q_min exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H₈₉ = 2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided as long as a threshold minimum safety factor value q_min > 2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to β_N values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to β_N > 4 by broadening the current profile. Furthermore, this path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.

View Accepted Manuscript (DOE)

Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE Office of Nuclear Energy (NE)

Grant/Contract Number:: FC02-04ER54698; AC52-07NA27344

OSTI ID:: 1354791

Alternate ID(s):: OSTI ID: 1838263
OSTI ID: 22738444
OSTI ID: 22925704

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 5 Vol. 57; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

References (52)

GATO: An MHD stability code for axisymmetric plasmas with internal separatrices Bernard, L. C.; Helton, F. J.; Moore, R. W. Computer Physics Communications, Vol. 24, Issue 3-4 https://doi.org/10.1016/0010-4655(81)90160-0	journal	December 1981
The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library Pankin, Alexei; McCune, Douglas; Andre, Robert Computer Physics Communications, Vol. 159, Issue 3 https://doi.org/10.1016/j.cpc.2003.11.002	journal	June 2004
The ARIES-AT advanced tokamak, Advanced technology fusion power plant Najmabadi, Farrokh; Abdou, A.; Bromberg, L. Fusion Engineering and Design, Vol. 80, Issue 1-4 https://doi.org/10.1016/j.fusengdes.2005.11.003	journal	January 2006
The external kink mode in diverted tokamaks Turnbull, A. D.; Hanson, J. M.; Turco, F. Journal of Plasma Physics, Vol. 82, Issue 3 https://doi.org/10.1017/S0022377816000568	journal	June 2016
Design and operation of the multipulse Thomson scattering diagnostic on DIII‐D (invited) Carlstrom, T. N.; Campbell, G. L.; DeBoo, J. C. Review of Scientific Instruments, Vol. 63, Issue 10 https://doi.org/10.1063/1.1143545	journal	October 1992
Improved charge coupled device detectors for the edge charge exchange spectroscopy system on the DIII-D tokamak Burrell, K. H.; Kaplan, D. H.; Gohil, P. Review of Scientific Instruments, Vol. 72, Issue 1 https://doi.org/10.1063/1.1319363	journal	January 2001
Magnetic diagnostic system of the DIII-D tokamak Strait, E. J. Review of Scientific Instruments, Vol. 77, Issue 2 https://doi.org/10.1063/1.2166493	journal	February 2006
Access to sustained high-beta with internal transport barrier and negative central magnetic shear in DIII-D Garofalo, A. M.; Doyle, E. J.; Ferron, J. R. Physics of Plasmas, Vol. 13, Issue 5 https://doi.org/10.1063/1.2185010	journal	May 2006
Motional Stark effect diagnostic expansion on DIII-D for enhanced current and Er profile measurements Holcomb, C. T.; Makowski, M. A.; Jayakumar, R. J. Review of Scientific Instruments, Vol. 77, Issue 10 https://doi.org/10.1063/1.2235812	journal	October 2006
The role of kinetic effects, including plasma rotation and energetic particles, in resistive wall mode stability Berkery, J. W.; Sabbagh, S. A.; Reimerdes, H. Physics of Plasmas, Vol. 17, Issue 8 https://doi.org/10.1063/1.3474925	journal	August 2010
Off-axis fishbone-like instability and excitation of resistive wall modes in JT-60U and DIII-D Okabayashi, M.; Matsunaga, G.; deGrassie, J. S. Physics of Plasmas, Vol. 18, Issue 5 https://doi.org/10.1063/1.3575159	journal	May 2011
Kinetic energy principle and neoclassical toroidal torque in tokamaks Park, Jong-Kyu Physics of Plasmas, Vol. 18, Issue 11 https://doi.org/10.1063/1.3662039	journal	November 2011
Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injection Ferron, J. R.; Holcomb, C. T.; Luce, T. C. Physics of Plasmas, Vol. 20, Issue 9 https://doi.org/10.1063/1.4821072	journal	September 2013
Measured improvement of global magnetohydrodynamic mode stability at high-beta, and in reduced collisionality spherical torus plasmas Berkery, J. W.; Sabbagh, S. A.; Balbaky, A. Physics of Plasmas, Vol. 21, Issue 5 https://doi.org/10.1063/1.4876610	journal	May 2014
Modeling of fast neutral-beam-generated ion effects on MHD-spectroscopic observations of resistive wall mode stability in DIII-D plasmas Turco, F.; Turnbull, A. D.; Hanson, J. M. Physics of Plasmas, Vol. 22, Issue 2 https://doi.org/10.1063/1.4906885	journal	February 2015
The direct criterion of Newcomb for the ideal MHD stability of an axisymmetric toroidal plasma Glasser, A. H. Physics of Plasmas, Vol. 23, Issue 7 https://doi.org/10.1063/1.4958328	journal	July 2016
Stability of high beta tokamak plasmas* Strait, E. J. Physics of Plasmas, Vol. 1, Issue 5 https://doi.org/10.1063/1.870691	journal	May 1994
Evolution of high β _p plasmas with improved stability and confinement* Politzer, P. A.; Casper, T.; Forest, C. B. Physics of Plasmas, Vol. 1, Issue 5 https://doi.org/10.1063/1.870937	journal	May 1994
Rotational and magnetic shear stabilization of magnetohydrodynamic modes and turbulence in DIII‐D high performance discharges Lao, L. L.; Burrell, K. H.; Casper, T. S. Physics of Plasmas, Vol. 3, Issue 5 https://doi.org/10.1063/1.871991	journal	May 1996
Growth of ideal magnetohydrodynamic modes driven slowly through their instability threshold: Application to disruption precursors Callen, J. D.; Hegna, C. C.; Rice, B. W. Physics of Plasmas, Vol. 6, Issue 8 https://doi.org/10.1063/1.873583	journal	August 1999
Suppression of resistive wall instabilities with distributed, independently controlled, active feedback coils Cates, C.; Shilov, M.; Mauel, M. E. Physics of Plasmas, Vol. 7, Issue 8 https://doi.org/10.1063/1.874223	journal	August 2000
Optimum safety factor profile for an advanced tokamak with negative central shear Lee, B. J.; Turnbull, A. D.; Taylor, T. S. Nuclear Fusion, Vol. 37, Issue 9 https://doi.org/10.1088/0029-5515/37/9/I07	journal	September 1997
High performance experiments in JT-60U reversed shear discharges Fujita, T.; Kamada, Y.; Ishida, S. Nuclear Fusion, Vol. 39, Issue 11Y https://doi.org/10.1088/0029-5515/39/11Y/302	journal	November 1999
Resistive wall mode dynamics and active feedback control in DIII-D Garofalo, A. M.; Chu, M. S.; Fredrickson, E. D. Nuclear Fusion, Vol. 41, Issue 9 https://doi.org/10.1088/0029-5515/41/9/305	journal	September 2001
Analysis and correction of intrinsic non-axisymmetric magnetic fields in high- DIII-D plasmas Garofalo, A. M.; Haye, R. J. La; Scoville, J. T. Nuclear Fusion, Vol. 42, Issue 11 https://doi.org/10.1088/0029-5515/42/11/308	journal	October 2002
Enhanced ITER resistive wall mode feedback performance using optimal control techniques Katsuro-Hopkins, O.; Bialek, J.; Maurer, D. A. Nuclear Fusion, Vol. 47, Issue 9 https://doi.org/10.1088/0029-5515/47/9/012	journal	August 2007
ITER startup studies in the DIII-D tokamak Jackson, G. L.; Casper, T. A.; Luce, T. C. Nuclear Fusion, Vol. 48, Issue 12 https://doi.org/10.1088/0029-5515/48/12/125002	journal	November 2008
Comprehensive control of resistive wall modes in DIII-D advanced tokamak plasmas Okabayashi, M.; Bogatu, I. N.; Chance, M. S. Nuclear Fusion, Vol. 49, Issue 12 https://doi.org/10.1088/0029-5515/49/12/125003	journal	October 2009
Off-axis neutral beam current drive for advanced scenario development in DIII-D Murakami, M.; Park, J. M.; Petty, C. C. Nuclear Fusion, Vol. 49, Issue 6 https://doi.org/10.1088/0029-5515/49/6/065031	journal	May 2009
A fusion development facility on the critical path to fusion energy Chan, V. S.; Stambaugh, R. D.; Garofalo, A. M. Nuclear Fusion, Vol. 51, Issue 8 https://doi.org/10.1088/0029-5515/51/8/083019	journal	July 2011
Ideal MHD stability and performance of ITER steady-state scenarios with ITBs Poli, F. M.; Kessel, C. E.; Chance, M. S. Nuclear Fusion, Vol. 52, Issue 6 https://doi.org/10.1088/0029-5515/52/6/063027	journal	June 2012
Overview of physics results from the conclusive operation of the National Spherical Torus Experiment Sabbagh, S. A.; Ahn, J. -W.; Allain, J. Nuclear Fusion, Vol. 53, Issue 10 https://doi.org/10.1088/0029-5515/53/10/104007	journal	September 2013
Steady state scenario development with elevated minimum safety factor on DIII-D Holcomb, C. T.; Ferron, J. R.; Luce, T. C. Nuclear Fusion, Vol. 54, Issue 9 https://doi.org/10.1088/0029-5515/54/9/093009	journal	August 2014
Modifications to ideal stability by kinetic effects in NSTX Berkery, J. W.; Sabbagh, S. A.; Bell, R. E. Nuclear Fusion, Vol. 55, Issue 12 https://doi.org/10.1088/0029-5515/55/12/123007	journal	October 2015
Phase folding of magnetic signals in tokamak plasmas Kim, J. S.; Chance, M. S.; Edgell, D. H. Plasma Physics and Controlled Fusion, Vol. 43, Issue 11 https://doi.org/10.1088/0741-3335/43/11/313	journal	October 2001
Resistive wall mode stabilization in slowly rotating high beta plasmas Reimerdes, H.; Garofalo, A. M.; Okabayashi, M. Plasma Physics and Controlled Fusion, Vol. 49, Issue 12B https://doi.org/10.1088/0741-3335/49/12B/S32	journal	November 2007
Effect of Collisionality on Kinetic Stability of the Resistive Wall Mode Berkery, J. W.; Sabbagh, S. A.; Betti, R. Physical Review Letters, Vol. 106, Issue 7 https://doi.org/10.1103/PhysRevLett.106.075004	journal	February 2011
Evidence for the Importance of Trapped Particle Resonances for Resistive Wall Mode Stability in High Beta Tokamak Plasmas Reimerdes, H.; Berkery, J. W.; Lanctot, M. J. Physical Review Letters, Vol. 106, Issue 21 https://doi.org/10.1103/PhysRevLett.106.215002	journal	May 2011
Improved plasma performance in tokamaks with negative magnetic shear Kessel, C.; Manickam, J.; Rewoldt, G. Physical Review Letters, Vol. 72, Issue 8 https://doi.org/10.1103/PhysRevLett.72.1212	journal	February 1994
Determination of the Noninductive Current Profile in Tokamak Plasmas Forest, C. B.; Kupfer, K.; Luce, T. C. Physical Review Letters, Vol. 73, Issue 18 https://doi.org/10.1103/PhysRevLett.73.2444	journal	October 1994
Wall Stabilization of High Beta Tokamak Discharges in DIII-D Strait, E. J.; Taylor, T. S.; Turnbull, A. D. Physical Review Letters, Vol. 74, Issue 13 https://doi.org/10.1103/PhysRevLett.74.2483	journal	March 1995
High Beta and Enhanced Confinement in a Second Stable Core VH-Mode Advanced Tokamak Turnbull, A. D.; Taylor, T. S.; Lin-Liu, Y. R. Physical Review Letters, Vol. 74, Issue 5 https://doi.org/10.1103/PhysRevLett.74.718	journal	January 1995
Improved Confinement with Reversed Magnetic Shear in TFTR Levinton, F. M.; Zarnstorff, M. C.; Batha, S. H. Physical Review Letters, Vol. 75, Issue 24 https://doi.org/10.1103/PhysRevLett.75.4417	journal	December 1995
Enhanced Confinement and Stability in DIII-D Discharges with Reversed Magnetic Shear Strait, E. J.; Lao, L. L.; Mauel, M. E. Physical Review Letters, Vol. 75, Issue 24 https://doi.org/10.1103/PhysRevLett.75.4421	journal	December 1995
Higher Fusion Power Gain with Current and Pressure Profile Control in Strongly Shaped DIII-D Tokamak Plasmas Lazarus, E. A.; Navratil, G. A.; Greenfield, C. M. Physical Review Letters, Vol. 77, Issue 13 https://doi.org/10.1103/PhysRevLett.77.2714	journal	September 1996
Quasisteady High-Confinement Reversed Shear Plasma with Large Bootstrap Current Fraction under Full Noninductive Current Drive Condition in JT-60U Fujita, T.; Ide, S.; Kamada, Y. Physical Review Letters, Vol. 87, Issue 8 https://doi.org/10.1103/PhysRevLett.87.085001	journal	July 2001
Reaching High Poloidal Beta at Greenwald Density with Internal Transport Barrier Close to Full Noninductive Current Drive Hobirk, J.; Wolf, R. C.; Gruber, O. Physical Review Letters, Vol. 87, Issue 8 https://doi.org/10.1103/PhysRevLett.87.085002	journal	August 2001
JET Quasistationary Internal-Transport-Barrier Operation with Active Control of the Pressure Profile Crisanti, F.; Litaudon, X.; Mailloux, J. Physical Review Letters, Vol. 88, Issue 14 https://doi.org/10.1103/PhysRevLett.88.145004	journal	March 2002
Resistive Wall Mode in Collisionless Quasistationary Plasmas Hu, Bo; Betti, R. Physical Review Letters, Vol. 93, Issue 10 https://doi.org/10.1103/PhysRevLett.93.105002	journal	September 2004
Reduced Critical Rotation for Resistive-Wall Mode Stabilization in a Near-Axisymmetric Configuration Reimerdes, H.; Garofalo, A. M.; Jackson, G. L. Physical Review Letters, Vol. 98, Issue 5 https://doi.org/10.1103/PhysRevLett.98.055001	journal	February 2007
Identification of a Low Plasma-Rotation Threshold for Stabilization of the Resistive-Wall Mode Takechi, M.; Matsunaga, G.; Aiba, N. Physical Review Letters, Vol. 98, Issue 5 https://doi.org/10.1103/PhysRevLett.98.055002	journal	February 2007
The ARIES Advanced and Conservative Tokamak Power Plant Study Kessel, C. E.; Tillack, M. S.; Najmabadi, F. Fusion Science and Technology, Vol. 67, Issue 1 https://doi.org/10.13182/FST14-794	journal	January 2015

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