Active feedback stabilization of the resistive wall mode on the DIII-D device

Okabayashi, M.; Bialek, J.; Chance, M. S.; Chu, M. S.; Fredrickson, E. D.; Garofalo, A. M.; Gryaznevich, M.; Hatcher, R.; Jensen, T. H.; Johnson, L. C.; Haye, R. J. La; Lazarus, E. A.; Makowski, M. A.; Manickam, J.; Navratil, G.A.; Scoville, J.T.; Strait, E.J.; Turnbull, A. D.; Walker, M.L.

doi:10.1063/1.1351823

Cited by 124 publications

(131 citation statements)

References 30 publications

(58 reference statements)

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“…Early DIII-D experiments 8,9 at beta above the no-wall stability limit did show behavior that is qualitatively similar to the modeling results in Ref. 1.…”

supporting

confidence: 82%

Comment on “The interaction of error fields and resistive wall modes” [Phys. Plasmas 11, 1019 (2004)]

2005

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“…Early DIII-D experiments 8,9 at beta above the no-wall stability limit did show behavior that is qualitatively similar to the modeling results in Ref. 1.…”

supporting

confidence: 82%

Comment on “The interaction of error fields and resistive wall modes” [Phys. Plasmas 11, 1019 (2004)]

2005

Self Cite

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“…Experimental results [41] are in good qualitative agreement with modelling predictions [42][43][44] that RWM stabilization is improved with radial magnetic field sensors inside the vacuum vessel wall as compared to radial field sensors outside the vessel wall and further improved with poloidal field sensors inside the vessel; these latter have faster time response and also do not couple to the field applied by the C-coil. A new set of twelve control coils inside the vacuum vessel is predicted [7,42,45] to allow feedback stabilization up to essentially the ideal wall limit even in the absence of rotation.…”

Section: Rwm Stabilizationsupporting

confidence: 69%

Overview of recent experimental results from the DIII-D advanced tokamak program

Team

2003

Nucl. Fusion

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The DIII-D research program is developing the scientific basis for advanced tokamak (AT) modes of operation in order to enhance the attractiveness of the tokamak as an energy producing system. Since the last international atomic energy agency (IAEA) meeting, we have made significant progress in developing the building blocks needed for AT operation: (1) we have doubled the magnetohydrodynamic (MHD) stable tokamak operating space through rotational stabilization of the resistive wall mode; (2) using this rotational stabilization, we have achieved β N H 89 10 for 4τ E limited by the neoclassical tearing mode (NTM); (3) using real-time feedback of the electron cyclotron current drive (ECCD) location, we have stabilized the (m, n) = (3, 2) NTM and then increased β T by 60%; (4) we have produced ECCD stabilization of the (2, 1) NTM in initial experiments; (5) we have made the first integrated AT demonstration discharges with current profile control using ECCD; (6) ECCD and electron cyclotron heating (ECH) have been used to control the pressure profile in high performance plasmas; and (7) we have demonstrated stationary tokamak operation for 6.5 s (36τ E ) at the same fusion gain parameter of β N H 89 /q 2 95 ∼ = 0.4 as ITER but at much higher q 95 = 4.2. We have developed general improvements applicable to conventional and AT operating modes: (1) we have an existence proof of a mode of tokamak operation, quiescent H-mode, which has no pulsed, edge localized modes (ELM) heat load to the divertor and which can run for long periods of time (3.8 s or 25τ E ) with constant density and constant radiated power; (2) we have demonstrated real-time disruption detection and mitigation for vertical disruption events using high pressure gas jet injection of noble gases; (3) we have found that the heat and particle fluxes to the inner strike points of balanced, double-null divertors are much smaller than to the outer strike points. We have made detailed investigations of the edge pedestal and scrape-off layer (SOL): (1) atomic physics and plasma physics both play significant roles in setting the width of the edge density barrier in H-mode; (2) ELM heat flux conducted to the divertor decreases as density increases; (3) intermittent, bursty transport contributes to cross field particle transport in the SOL of H-mode and, especially, L-mode plasmas.

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“…As previously shown [28], plasma rotation is sufficient to stabilize this mode up to the perfectly conducting wall limit. In the absence of sufficient rotation, this mode is amenable to active feedback control due to the slow growth rate [29]. There is also a self-consistent plasma response to any non-axisymmetric external magnetic perturbations that acts to drag down the rotation, thereby increasing the growth rate of the mode [30].…”

Section: Stabilization Of Resistive Wall Modesmentioning

confidence: 99%

Development of burning plasma and advanced scenarios in the DIII-D tokamak

Luce

2005

Nucl. Fusion

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Abstract. Significant progress in the development of burning plasma scenarios, steady-state scenarios at high fusion performance, and basic tokamak physics has been made by the DIII-D Team. Discharges similar to the ITER baseline scenario have demonstrated normalized fusion performance nearly 50% higher than required for Q = 10 in ITER, under stationary conditions. Discharges that extrapolate to Q ~ 10 for longer than one hour in ITER at reduced current have also been demonstrated in DIII-D under stationary conditions. Proof of high fusion performance with full noninductive operation has been obtained. Underlying this work are studies validating approaches to confinement extrapolation, disruption avoidance and mitigation, tritium retention, ELM avoidance, and operation above the no-wall pressure limit. In addition, the unique capabilities of the DIII-D facility have advanced studies of the sawtooth instability with unprecedented time and space resolution, threshold behavior in the electron heat transport, and rotation in plasmas in the absence of external torque.

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Active feedback stabilization of the resistive wall mode on the DIII-D device

Abstract: This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.

Cited by 124 publications

References 30 publications

Comment on “The interaction of error fields and resistive wall modes” [Phys. Plasmas 11, 1019 (2004)]

Comment on “The interaction of error fields and resistive wall modes” [Phys. Plasmas 11, 1019 (2004)]

Overview of recent experimental results from the DIII-D advanced tokamak program

Development of burning plasma and advanced scenarios in the DIII-D tokamak

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