The effect of resonant magnetic perturbations on the divertor heat and particle fluxes in MAST

Abstract

Edge localised modes (ELMs) are a concern for future devices, such as ITER, due to the large transient heat loads they generate on the divertor surfaces which could limit the operational time of the device. This paper discusses the application of resonant magnetic perturbations (RMPs) as a mechanism for ELM control on MAST. Experiments have been performed using an n=3 toroidal mode number perturbation and measurements of the strike point splitting performed. The measurements have been made using both infrared and visible imaging to measure the heat and particle flux to the divertor. The measured profiles have shown clear splitting in L-mode which compares well with the predication of the splitting location from modelling including the effect of screening. The splitting of the strike point has also been studied as a function of time during the ELM. The splitting varies during the ELM, being the strongest at the time of the peak heat flux and becoming more filamentary at the end of the ELM (200 microseconds after the peak midplane D(alpha) emission). Variation in the splitting profiles has also been seen, with some ELMs showing clear splitting and others no splitting. A possible explanation of this effect is proposed, and supported by modelling, which concerns the relative phase between the RMP field and the ELM filament location.

arXiv comment26 pages, 26 figures. Presented at the Stochasticity in Fusion Plasmas Workshop, Aachen, March 2013

References in corpus (6)

• Resonant magnetic perturbations and divertor footprints in poloidally diverted tokamaks
• Model for screening of resonant magnetic perturbations by plasma in a realistic tokamak geometry and its impact on divertor strike points
• Effect of resonant magnetic perturbations with toroidal mode numbers of 4 and 6 on ELMs in single null H-mode plasmas in MAST
• Divertor heat fluxes and profiles during mitigated and unmitigated Edge Localised Modes (ELMs) on the Mega Amp Spherical Tokamak (MAST)
• Strike point splitting induced by the application of magnetic perturbations on MAST
• Effect of resonant magnetic perturbations on ELMs in connected double null plasmas in MAST

Cited by in corpus (3)

• The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas
• Divertor Heat Load in ASDEX Upgrade L-Mode in Presence of External Magnetic Perturbation
• ELM mitigation via rotating resonant magnetic perturbations on MAST