The effect of tangled magnetic fields on instabilities in tokamak plasmas

Tangled Magnetic Fields in Astro- and Plasma Physics; Quantised Flux in Tightly Knotted and Linked Systems

Thornton, A.J.^1 ; Kirk, A.^1 ; Harrison, J.R.^1 ; Cahyna, P.^2 ; Chapman, I.T.^1 ; Nardon, E.^3

EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon

0X14 3DB, United Kingdom^1

Institute of Plasma Physics AS CR V.v.i., Association EURATOM/IPP.CR, Prague, Czech Republic^2

Association Euratom/CEA, CEA Cadarache, St. Paul-lez-Durance

F-13108, France^3

关键词: Fusion devices;    High-pressure gradient;    Localised;    Plasma response;    Resonant magnetic perturbations;    Spherical Tokamak;    Tokamak plasmas;    Visible light;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/544/1/012010/pdf
DOI  :  10.1088/1742-6596/544/1/012010

来源: IOP

【 摘 要 】

The high pressure gradients in the edge of a tokamak plasma can lead to the formation of explosive plasma instabilities known as edge localised modes (ELMs). The control of ELMs is an important requirement for the next generation of fusion devices such as ITER. Experiments performed on the Mega Amp Spherical Tokamak (MAST) at Culham have shown that the application of non-axisymetric resonant magnetic perturbations (RMPs) can be used to mitigate ELMs. During the application of the RMPs, clear structures are observed in visible- light imaging of the X-point region. These lobes, or tangles, have been observed for the first time and their appearance is correlated with the mitigation of ELMs. Tangle formation is seen to be associated with the RMPs penetrating the plasma and may be important in explaining why the ELM frequency increases during ELM mitigation. Whilst the number and location of the tangles can be explained by vacuum magnetic field modelling, obtaining the correct radial extent of the tangles requires the plasma response to be taken into account.