English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

It is known that magnetic perturbations can mitigate edge localized modes(ELMs) in experiments, for example MAST (Kirk et al 2013 Nucl. Fusion 53043007). One hypothesis is that the magnetic perturbations cause a threedimensional corrugation of the plasma and this corrugated plasma has differentstability properties to peeling-ballooning modes compared to an axisymmetricplasma. It has been shown in an up-down symmetric plasma that magneticperturbations in tokamaks will break the usual axisymmetry of the plasmacausing three dimensional displacements (Chapman et al 2012 Plasma Phys.Control. Fusion 54 105013). We produce a free boundary three-dimensionalequilibrium of a lower single null MAST relevant plasma using VMEC (S PHirshman and J C Whitson 1983 Phys. Fluids 26 3553). The current and pressureprofiles used for the modelling are similar to those deduced from axisymmetricanalysis of experimental data with ELMs. We focus on the effect of applying$n=3$ and $n=6$ magnetic perturbations using the RMP coils. A midplanedisplacement of over $\pm 1$ cm is seen when the full current is applied. Thecurrent in the coils is scaned and a linear relationship between coil currentand midplane displacement is found. The effect of this non-axisymmetricequilibrium on infinite $n$ ballooning stability is investigated using COBRA (RSanchez et al 2000 J. Comput. Phys. 161 576-588).

Modelling of three dimensional equilibrium and stability of MAST plasmas with magnetic perturbations using VMEC and COBRA