Multiple branches of resistive wall mode instability in a resistive plasma

Yang, Shengcai; Liu, Y. Q.; Hao, G. Z.; Wang, Z. X.; He, Huimin; Wang, A. K.; Xu, M.

doi:10.1063/1.5007819

Cited by 3 publications

(2 citation statements)

References 50 publications

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“…It is well known that, at W add = 0 and with other simplifications, equation ( 31) may reduce to equation (28), see [54][55][56], for example. This, however, is inapplicable to experimentally observed RWMs developing much before the state with q w < 1 could be reached [50], which explains a number of efforts to incorporate any possible non-ideal effect, plasma rotation and inertia.…”

Section: Models For the Sideways Forcementioning

confidence: 99%

“…This, however, is inapplicable to experimentally observed RWMs developing much before the state with q w < 1 could be reached [50], which explains a number of efforts to incorporate any possible non-ideal effect, plasma rotation and inertia. Particular realizations of equation (31) with W add = 0 representing various choices of dissipation can be found in [50,51,[54][55][56][57][58][59][60][61].…”

Section: Models For the Sideways Forcementioning

confidence: 99%

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Models and scalings for the disruption forces in tokamaks

Pustovitov¹

2022

Nucl. Fusion

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The study is devoted to theoretical analysis of the models for calculating the disruption forces in tokamaks. It is motivated by the necessity of reliable predictions for ITER. The task includes the evaluation of the existing models, resolution of the conflicts between them, elimination of contradictions by proper improvements, elaboration of recommendations for dedicated studies. Better qualities of the modelling and higher accuracy are the ultimate theoretical goals. In recent years, there was a steady progress in developing a physics basis for calculating the forces, which gave rise to new trends and ideas. It was discovered, in particular, that the wall resistivity, penetration of the magnetic perturbation through the wall, the poloidal current induced in the wall, the kink-mode coupling, plasma position in the vacuum vessel must be the elements essentially affecting the disruption forces. These and related predictions along with earlier less sophisticated concepts and results are analyzed here

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Section: Models For the Sideways Forcementioning

confidence: 99%

Section: Models For the Sideways Forcementioning

confidence: 99%

Models and scalings for the disruption forces in tokamaks

Pustovitov¹

2022

Nucl. Fusion

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Active control of resistive wall mode via modification of external tearing index

et al. 2021

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Modification of the external tearing index, Δext′, by magnetic feedback is analytically investigated for the purpose of controlling the resistive plasma resistive wall mode (RP-RWM). The matching method is pursued by deriving expressions for the close-loop Δext′ and by linking it to the counterpart from the inner layer. Various feedback coil configurations are found to generally reduce Δext′ and stabilize the RWM, with either proportional or derivative control. Feedback modification of Δext′ is found to be generally independent of the inner layer resistive interchange index DR, confirming that feedback action primarily modifies the solution in the outer ideal region for the RP-RWM. Exception occurs when either the inner layer favorable curvature effect becomes sufficiently large or the feedback action is sufficiently strong to introduce a rotating RP-RWM in the static plasma, leading to complex-valued close-loop Δext′. The perturbed magnetic energy dissipation in the outer region, associated with the eddy current in the resistive wall, is identified as the key physics reason for feedback induced complex Δext′. Similar results are also obtained for active control of the external kink instability, whose open-loop growth rate is significantly reduced by inclusion of the plasma resistivity. Within the single poloidal harmonic approximation, which is most suitable for the matching approach, external active coils combined with poloidal sensors are often found to be more efficient for feedback stabilization of the mode at large proportional gain values. This counter-intuitive result is explained as the lack of (non-resonant) poloidal harmonics for proper description of the feedback coil geometry.

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A time-spectral method for initial-value problems using a novel spatial subdomain scheme

Lindvall

Scheffel

2018

Cogent Mathematics & Statistics

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We analyse a new subdomain scheme for a time-spectral method for solving initial boundary value problems. Whilst spectral methods are commonplace for spatially dependent systems, finite difference schemes are typically applied for the temporal domain. The Generalized Weighted Residual Method (GWRM) is a fully spectral method in that it spectrally decomposes all specified domains, including the temporal domain, with multivariate Chebyshev polynomials. The Common Boundary-Condition method (CBC) is a spatial subdomain scheme that solves the physical equations independently from the global connection of subdomains. It is here evaluated against two finite difference methods. For the linearised Burger equation the CBC-GWRM is ∼ 30% faster and ∼ 50% more memory efficient than the semi implicit Crank-Nicolson method at a maximum error ∼ 10 −5 . For a forced wave equation the CBC-GWRM manages to average efficiently over the small time-scale in the entire temporal domain. The CBC-GWRM is also applied to the linearised ideal magnetohydrodynamic (MHD) equations for a screw pinch equilibrium. The growth rate of the most unstable mode was efficiently computed with an error < 0.1%.

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Multiple branches of resistive wall mode instability in a resistive plasma

Cited by 3 publications

References 50 publications

Models and scalings for the disruption forces in tokamaks

Models and scalings for the disruption forces in tokamaks

Active control of resistive wall mode via modification of external tearing index

A time-spectral method for initial-value problems using a novel spatial subdomain scheme

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