Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection

E. J. Strait, A. M. Garofalo, G. L. Jackson, M. Okabayashi, H. Reimerdes, Ming-Sheng Chu, R. Fitzpatrick, R. J. Groebner, Y. In, R. J. Lahaye, M. J. Lanctot, Y. Q. Liu, G. A. Navratil, W. M. Solomon, H. Takahashi

Research output: Contribution to journalArticle

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Abstract

Recent experiments in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] show that the resistive wall mode (RWM) can be stabilized by smaller values of plasma rotation than previously reported. Stable discharges have been observed with beta up to 1.4 times the no-wall kink stability limit and ion rotation velocity (measured from CVI emission) less than 0.3% of the Alfv́n speed at all integer rational surfaces, in contrast with previous DIII-D experiments that indicated critical values of 0.7%-2.5% of the local Alfv́n speed. Preliminary stability calculations for these discharges, using ideal magnetohydrodynamics with a drift-kinetic dissipation model, are consistent with the new experimental results. A key feature of these experiments is that slow plasma rotation was achieved by reducing the neutral beam torque. Earlier experiments with strong neutral beam torque used "magnetic braking" by applied magnetic perturbations to slow the rotation, and resonant effects of these perturbations may have led to a larger effective rotation threshold. In addition, the edge rotation profile may have a critical role in determining the RWM stability of these low-torque plasmas.

Original languageEnglish
Article number056101
JournalPhysics of Plasmas
Volume14
Issue number5
DOIs
Publication statusPublished - 2007 Jun 11

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beam injection
neutral beams
stabilization
torque
chemical vapor infiltration
perturbation
braking
magnetohydrodynamics
integers
dissipation
fusion
thresholds
kinetics
profiles
ions

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Strait, E. J., Garofalo, A. M., Jackson, G. L., Okabayashi, M., Reimerdes, H., Chu, M-S., ... Takahashi, H. (2007). Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection. Physics of Plasmas, 14(5), [056101]. https://doi.org/10.1063/1.2472599
Strait, E. J. ; Garofalo, A. M. ; Jackson, G. L. ; Okabayashi, M. ; Reimerdes, H. ; Chu, Ming-Sheng ; Fitzpatrick, R. ; Groebner, R. J. ; In, Y. ; Lahaye, R. J. ; Lanctot, M. J. ; Liu, Y. Q. ; Navratil, G. A. ; Solomon, W. M. ; Takahashi, H. / Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection. In: Physics of Plasmas. 2007 ; Vol. 14, No. 5.
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abstract = "Recent experiments in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] show that the resistive wall mode (RWM) can be stabilized by smaller values of plasma rotation than previously reported. Stable discharges have been observed with beta up to 1.4 times the no-wall kink stability limit and ion rotation velocity (measured from CVI emission) less than 0.3{\%} of the Alfv́n speed at all integer rational surfaces, in contrast with previous DIII-D experiments that indicated critical values of 0.7{\%}-2.5{\%} of the local Alfv́n speed. Preliminary stability calculations for these discharges, using ideal magnetohydrodynamics with a drift-kinetic dissipation model, are consistent with the new experimental results. A key feature of these experiments is that slow plasma rotation was achieved by reducing the neutral beam torque. Earlier experiments with strong neutral beam torque used {"}magnetic braking{"} by applied magnetic perturbations to slow the rotation, and resonant effects of these perturbations may have led to a larger effective rotation threshold. In addition, the edge rotation profile may have a critical role in determining the RWM stability of these low-torque plasmas.",
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Strait, EJ, Garofalo, AM, Jackson, GL, Okabayashi, M, Reimerdes, H, Chu, M-S, Fitzpatrick, R, Groebner, RJ, In, Y, Lahaye, RJ, Lanctot, MJ, Liu, YQ, Navratil, GA, Solomon, WM & Takahashi, H 2007, 'Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection', Physics of Plasmas, vol. 14, no. 5, 056101. https://doi.org/10.1063/1.2472599

Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection. / Strait, E. J.; Garofalo, A. M.; Jackson, G. L.; Okabayashi, M.; Reimerdes, H.; Chu, Ming-Sheng; Fitzpatrick, R.; Groebner, R. J.; In, Y.; Lahaye, R. J.; Lanctot, M. J.; Liu, Y. Q.; Navratil, G. A.; Solomon, W. M.; Takahashi, H.

In: Physics of Plasmas, Vol. 14, No. 5, 056101, 11.06.2007.

Research output: Contribution to journalArticle

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T1 - Resistive wall mode stabilization by slow plasma rotation in DIII-D tokamak discharges with balanced neutral beam injection

AU - Strait, E. J.

AU - Garofalo, A. M.

AU - Jackson, G. L.

AU - Okabayashi, M.

AU - Reimerdes, H.

AU - Chu, Ming-Sheng

AU - Fitzpatrick, R.

AU - Groebner, R. J.

AU - In, Y.

AU - Lahaye, R. J.

AU - Lanctot, M. J.

AU - Liu, Y. Q.

AU - Navratil, G. A.

AU - Solomon, W. M.

AU - Takahashi, H.

PY - 2007/6/11

Y1 - 2007/6/11

N2 - Recent experiments in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] show that the resistive wall mode (RWM) can be stabilized by smaller values of plasma rotation than previously reported. Stable discharges have been observed with beta up to 1.4 times the no-wall kink stability limit and ion rotation velocity (measured from CVI emission) less than 0.3% of the Alfv́n speed at all integer rational surfaces, in contrast with previous DIII-D experiments that indicated critical values of 0.7%-2.5% of the local Alfv́n speed. Preliminary stability calculations for these discharges, using ideal magnetohydrodynamics with a drift-kinetic dissipation model, are consistent with the new experimental results. A key feature of these experiments is that slow plasma rotation was achieved by reducing the neutral beam torque. Earlier experiments with strong neutral beam torque used "magnetic braking" by applied magnetic perturbations to slow the rotation, and resonant effects of these perturbations may have led to a larger effective rotation threshold. In addition, the edge rotation profile may have a critical role in determining the RWM stability of these low-torque plasmas.

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