UKAEA Journals

Showing 1 - 10 of 12 Journals Results
2020
UKAEA-CCFE-PR(21)62

Reconstructions of plasma equilibria using magnetic sensors and a Dα constraint were routine during operation of the MAST spherical tokamak, but reconstructions using kinetic profiles was not. These are necessary for stability and disruption analysis of the MAST database, as well as going forward for operation in the upgrade to the device, MAST-U.…

Preprint
2018

Access conditions for full suppression of edge localised modes (ELMs) by magnetic perturbations (MP) in low density high confinement mode (H-mode) plasmas are studied in the ASDEX Upgrade tokamak. The main empirical requirements for full ELM suppression in our experiments are: 1. The poloidal spectrum of the MP must be aligned for best plasma respo…

Published
2018
UKAEA-CCFE-PR(20)110

The role of magnetic perturbations generated by filaments in the scrape-off layer is investigated by performing simulations of 3D seeded filaments with an electromagnetic numerical code which includes sheath boundary conditions. Depending on the plasma , three smoothly connecting regimes were identified: an electrostatic regime where the magnet…

Preprint Published
2019
UKAEA-CCFE-PR(20)02

Shear strain profiles along slip bands in a modified Rolls-Royce nickel superalloy (RR1000) were analyzed for tensile sample deformed by 2%. The strain increased with distance away from a grain boundary (GB), with maximum shear strain towards the center of the grain, indicating that dislocation nucleation generally occurred in the grain interior. T…

Preprint Purchase
2019
UKAEA-CCFE-PR(19)18

A numerical survey of the plasma response in ASDEX Upgrade ELM control experiments is conducted, to clarify the role of triangularity in the suppression mechanism. The pedestal pressure increases with triangularity consistent with previous work [2], which modestly boosts the peeling response. However, the peeling response decreases with increasi…

Preprint Published
2018
UKAEA-CCFE-PR(18)69

The impact of the three-dimensional (3D) tokamak geometry from external magnetic perturbations (MPs) on the local edge stability has been examined in high confinement mode (H-mode) plasmas with edge localised modes (ELMs) in ASDEX Upgrade. The 3D geometry has been probed using rigidly rotating MP fields. The measured distortions of the plasma bound…

Preprint Published
2017
CCFE-PR(17)70

It has been previously demonstrated in (Li et al 2016 Nuclear Fusion 56 126007) that the optimum upper/lower coil phase shift ΔΦopt for alignment of RMP coils for ELM mitigation depends sensitively on q95, and other equilibrium plasma parameters. Therefore, ΔΦopt is expected to vary widely during the current ramp …

Preprint Published
2017

Extensive modelling efforts of the plasma response to the resonant magnetic perturbation fields, utilized for controlling the edge localized mode (ELM), help to identify the edge-peeling response as a key factor, which correlates to the observed ELM mitigation in several tokamak devices, including MAST, ASDEX Upgrade, EAST, and HL-2A. The recently …

Published
2016
CCFE-PR(16)47

Resonant magnetic perturbations (RMP) have extensively been demonstrated as a plausible technique for mitigating or suppressing large edge localized modes (ELMs). Associated with this is a substantial amount of theory and modelling efforts during recent years. Various models describing the plasma response to the RMP fields have been proposed in the…

Preprint 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