UKAEA Journals

Showing 21 - 30 of 94 Journals Results
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 …

Published
2016
CCFE-PR(16)07

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…

Preprint Published
2016
CCFE-PR(16)08

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…

Preprint Published
2015
CCFE-PR(15)101

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 …

Preprint Published
2015
CCFE-PR(15)91

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…

Preprint Published
2015
CCFE-PR(15)90

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…

Preprint Published
2015
CCFE-PR(15)84.

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…

Preprint Published
2015
CCFE-PR(15)82

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…

Preprint Published
2015
CCFE-PR(15)81

Detailed measurements of the plasma’s 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 …

Preprint Published
2015
CCFE-PR(15)75

The magnetohydrodynamic-kinetic hybrid theory has been extensively and successfully applied for interpreting experimental observations of macroscopic, low frequency instabilities, such as the resistive wall mode, in fusion plasmas. In this work, it is discovered that an analytic version of the hybrid formulation predicts a bifurcation of the mode d…

Preprint Published