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| 2. |
- Liu, Yueqiang, 1971, et al.
(författare)
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Resistive wall mode control code maturity: progress and specific examples
- 2010
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 52:10
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Tidskriftsartikel (refereegranskat)abstract
- Two issues of the resistive wall mode (RWM) control code maturity are addressed: the inclusion of advanced mode damping physics beyond the ideal MHD description, and the possibility of taking into account the influence of 3D features of the conducting structures on the mode stability and control. Examples of formulations and computational results are given, using the MARS-F/K codes and the CarMa code. The MARS-K calculations for a DIII-D plasma shows that the fast ion contributions, which can give additional drift kinetic stabilization in the perturbative approach, also drive an extra unstable branch of mode in the self-consistent kinetic modelling. The CarMa modelling for the ITER steady state advanced plasmas shows about 20% reduction in the RWM growth rate by the volumetric blanket modules. The multi-mode analysis predicts a weak interaction between the n = 0 and the n = 1 RWMs, due to the 3D ITER walls. The CarMa code is also successfully applied to model the realistic feedback experiments in RFX.
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| 4. |
- Lanctot, M.J., et al.
(författare)
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Measurement and modeling of three-dimensional equilibriua in DIII-D
- 2011
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Ingår i: Physics of Plasmas. - 1089-7674 .- 1070-664X. ; 18, s. 056121-
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Tidskriftsartikel (refereegranskat)abstract
- A detailed experiment-theory comparison reveals that linear ideal MHD theory is in quantitative agreement with external magnetic and internal soft x-ray measurements of the plasma response to externally applied non-axisymmetric fields over a broad range of beta and rotation. This result represents a significant step toward the goal of advancing the understanding of three-dimensional tokamak equilibria. Both the magnetic and soft x-ray measurements show the driven plasma perturbation increases linearly with the applied perturbation, suggesting the relevance of linear plasma response models. The magnetic and soft x-ray measurements are made at multiple toroidal and poloidal locations, allowing well resolved measurements of the global structure. The comparison also highlights the need to include kinetic effects in the MHD model once beta exceeds 80% of the kink mode limit without a conducting wall. Two distinct types of response fields are identified by the linear ideal MHD model: one that consists of localized currents at the rational surfaces that cancel the applied resonant field and another that is excited by the components of the external field that couple to the kink mode. Numerical simulations show these two fields have similar amplitudes in ITER-shaped DIII-D discharges where n = 3 fields are used to suppress edge localized modes.
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| 5. |
- Liu, Yueqiang, 1971, et al.
(författare)
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Toroidal modelling of plasma response and RMP field penetration
- 2012
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 54:12, s. 124013-
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Tidskriftsartikel (refereegranskat)abstract
- The penetration dynamics of the resonant magnetic perturbation (RMP) field is sim-ulated in the full toroidal geometry, under realistic plasma conditions in MAST experiments.The physics associated with several aspects of the RMP penetration - the plasma responseand rotational screening, the resonant and non-resonant torques and the toroidal momentumbalance - are highlighted. In particular, the plasma response is found to significantly amplifythe non-resonant component of the RMP field for some of the MAST plasmas. A fast rotatingplasma, in response to static external magnetic fields, experiences a more distributed electro-magnetic torque due to the resonance with continuum waves in the plasma. At fast plasmaflow (such as for the MAST plasma), the electromagnetic torque is normally dominant overthe neoclassical toroidal viscous (NTV) torque. However, at sufficiently slow plasma flow,the NTV torque can play a significant role in the toroidal momentum balance, thanks to theprecession drift resonance enhanced, so called superbanana plateau regime.
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| 6. |
- Lanctot, M. J., et al.
(författare)
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Validation of the linear ideal magnetohydrodynamic model of three-dimensional tokamak equilibria
- 2010
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 17:3, s. 030701-
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Tidskriftsartikel (refereegranskat)abstract
- The first quantitative comparison of linear ideal magnetohydrodynamic (MHD) theory with external magnetic measurements of the nonaxisymmetric plasma perturbation driven by external long-wavelength magnetic fields in high-temperature tokamak plasmas is presented. The comparison yields good (within 20%) agreement for plasma pressures up to ∼ 75% of the ideal stability limit calculated without a conducting wall. For higher plasma pressures, the ideal MHD model tends to overestimate the perturbed field indicating the increasing importance of stabilizing nonideal effects.
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