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, M. S.; Fitzpatrick, Richard; Groebner, R. J.; In, Y.; LaHaye, R.J.; Lanctot, M. J.; Liu, Y. Q.; Navratil, G.A.; Solomon, W. M.; Takahashi, H.

doi:10.1063/1.2472599

Cited by 61 publications

(91 citation statements)

References 27 publications

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“…1 The n =1 RWM has been predicted to be unstable in the ITER 2 steady state scenario-4, just beyond the target plasma pressure, unless a sufficiently fast plasma rotation, or a magnetic feedback system, is available. 3 While the feedback stabilization of the RWM has been well understood in theory and demonstrated in several tokamaks and RFP devices, the physics of rotational stabilization of the RWM is not completely resolved, partly because new experimental evidence 4,5 contradicts previous theories based on the magnetohydrodynamic ͑MHD͒ description of the mode.…”

Section: Toroidal Self-consistent Modeling Of Drift Kinetic Effects Omentioning

confidence: 98%

Toroidal self-consistent modeling of drift kinetic effects on the resistive wall mode

et al. 2008

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A self-consistent kinetic model is developed to study the stability of the resistive wall mode in toroidal plasmas. This model is compared with other models based on perturbative approaches. The degree of the kinetic modification to the stability of the mode depends on the plasma configurations. Both stabilizing and destabilizing kinetic effects are observed. The nonperturbative approach, with a self-consistent inclusion of the eigenfunctions and the eigenvalues of the resistive wall mode, normally finds less stabilization than the perturbative approach.

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Section: Toroidal Self-consistent Modeling Of Drift Kinetic Effects Omentioning

confidence: 98%

Toroidal self-consistent modeling of drift kinetic effects on the resistive wall mode

et al. 2008

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“…Recent experiments with nearly balanced NBI [54][55][56] have found a critical velocity to stabilise the RWM well below that found in the magnetic braking experiments [50,52]. Furthermore, preliminary results from NSTX suggest that operation above the no-wall limit can be attained even with no plasma rotation at the resonant q = 2 surface [57].…”

Section: Modelling Rwm Stabilitymentioning

confidence: 99%

Macroscopic stability of high β MAST plasmas

et al. 2011

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Abstract. The high-beta capability of the spherical tokamak, coupled with a suite of world-leading diagnostics on MAST, has facilitated significant improvements in the understanding of performance-limiting core instabilities in high performance plasmas. For instance, the newly installed Motional Stark Effect (MSE) diagnostic, with radial resolution < 25mm, has enabled detailed study of saturated long-lived modes in hybrid scenarios. Similarly, the upgraded Thomson Scattering (TS) system, with radial resolution < 10mm and the possibility of temporal resolution of 1µs, has allowed detailed analysis of the density and temperature profiles during transient activity in the plasma, such as at a sawtooth crash. High resolution Charge Exchange Recombination Spectroscopy (CXRS) provided measurement of rotation braking induced by both applied magnetic fields and by magnetohydrodynamic (MHD) instabilities, allowing tests of neoclassical toroidal viscosity theory predictions. Finally, MAST is also equipped with internal and external coils that allow non-axisymmetric fields to be applied for active MHD spectroscopy of instabilities near the no-wall beta limit. Such resonant field amplification measurements suggest that MAST has been able to operate above the no-wall limit. In order to access such high pressures, the resistive wall mode must be damped, and so numerical modelling has focussed on assessing the kinetic damping of the mode and its nonlinear interaction with other instabilities. The enhanced understanding of the physical mechanisms driving deleterious MHD activity given by these leading-edge capabilities has provided guidance to optimise operating scenarios for improved plasma performance. Macroscopic Stability of High β MAST plasmas2 Figure 1. Virtuous cycle when high β N plasmas are accessed; giving rise to enhanced bootstrap fraction, allowing lower internal inductance and increased shaping which further enhances the non-inductively driven fraction, allowing the safety factor on axis to be raised, in turn permitting higher pressure plasmas.

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“…[11][12][13][14] Recent experiments with nearly balanced neutral beam injection (NBI) 11,12 have found a critical velocity for RWM stabilisation well below that found in previous magnetic braking experiments. 10 Consequently, in order to make reliable extrapolation to ITER, it is crucial to understand the passive stabilisation allowing operation above the predicted no-wall stability limits.…”

Section: Introductionmentioning

confidence: 99%

Kinetic damping of resistive wall modes in ITER

et al. 2012

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Full drift kinetic modelling including finite orbit width effects has been used to assess the passive stabilisation of the resistive wall mode (RWM) that can be expected in the ITER advanced scenario. At realistic plasma rotation frequency, the thermal ions have a stabilising effect on the RWM, but the stability limit remains below the target plasma pressure to achieve Q ¼ 5. However, the inclusion of damping arising from the fusion-born alpha particles, the NBI ions, and ICRH fast ions extends the RWM stability limit above the target b for the advanced scenario. The fast ion damping arises primarily from finite orbit width effects and is not due to resonance between the particle frequencies and the instability. [http://dx.

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

Cited by 61 publications

References 27 publications

Toroidal self-consistent modeling of drift kinetic effects on the resistive wall mode

Toroidal self-consistent modeling of drift kinetic effects on the resistive wall mode

Macroscopic stability of high β MAST plasmas

Kinetic damping of resistive wall modes in ITER

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