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CCFE-PR(16)252016
The high-frequency noise measured by magnetic sensors, at levels above the typical frequency of resistive wall modes, is analyzed across a range of present tokamak devices including DIII-D, JET, MAST, ASDEX Upgrade, JT-60U, and NSTX. A high-pass filter enables identification of the noise component with Gaussian-like statistics that shares certain c…
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2016
Cold and hot vertical displacement events (VDEs) are frequently related to the disruption of vertically-elongated tokamaks. The weak poloidal magnetic field around the null-points of a snowflake divertor configuration may influence the vertical displacement process. In this paper, the major disruption with a cold VDE and the vertical disruption in …
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CCFE-PR(16)072016
The plasma response to the vacuum resonant magnetic perturbation (RMP) fields, produced by the ELM control coils in ASDEX Upgrade experiments, is computationally modelled using the MARS-F/K codes [Liu Y.Q. et al 2000 Phys. Plasmas 7 3681; Liu Y.Q. et al 2008 Phys. Plasmas 15 112503]. A systematic investigation is carried out, considering various pl…
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CCFE-PR(16)082016
Computations in toroidal geometry are systematically performed for the plasma response to 3D magnetic perturbations, produced by ferritic inserts (FIs) and test blanket modules (TBMs), for four ITER plasma scenarios: the 15MA baseline, the 12.5MA hybrid, the 9MA steady state, and the 7.5MA half-field Helium plasma. Due to broad toroidal spectrum of…
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CCFE-PR(15)1012015
Tokamaks are traditionally viewed as axisymmetric devices. However this is not always true, for example in the presence of saturated instabilities, error fields, or resonant magnetic perturbations (RMPs) applied for edge localized mode (ELM) control. We use the VMEC code (Hirshman and Whitson 1983 Phys. Fluids 26 3553) to …
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CCFE-PR(15)912015
Drift kinetic stabilization of the resistive wall mode (RWM) is computationally investigated using the MHD-kinetic hybrid code MARS-K, following the non-perturbative approach [Liu et al., Phys. Plasmas 15, 112503 (2008)], for both reversed field pinch (RFP) and tokamak plasmas. Various kinetic resonances between the mode and the guiding center drif…
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CCFE-PR(15)902015
It has been shown on several tokamaks that application of a Resonant Magnetic Perturbation (RMP) eld on plasma can under certain conditions lead to suppression or mitigation of Edge-Localized Mode (ELM) instabilities. Due to the rotation of the plasma in the RMP eld reference system, currents are induced on resonant surfaces within the plasma, co…
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CCFE-PR(15)84.2015
Within the single fluid resistive magnetohydrodynamic model, systematic toroidal modelling efforts are devoted to investigate the plasma response induced screening of the applied external 3D magnetic field perturbations in the presence of sheared toroidal flow. One particular issue of interest is addressed, when the local flow speed approaches zero…
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CCFE-PR(15)822015
An unstable fishbone-like non-resonant external kink mode (FLEM) is numerically found to be driven by the precessional drift motion of trapped energetic particles (EPs) in both RFP and Tokamak plasmas. The FLEM originates from a stable external ideal kink mode, which is stabilized by a close-fitting ideal conducting wall. In the presence of a suffi…
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CCFE-PR(15)812015
Detailed measurements of the plasmas response to applied magnetic perturbations provide experimental evidence that the form of three-dimensional (3D) tokamak equilibria, with toroidal mode number n = 1, is determined by multiple stable kink modes at high-pressure. For pressures greater than the ideal magnetohydrodynamic (MHD) stability limit, as …
Showing 51 - 60 of 125 UKAEA Paper Results