Parameter dependence of ELM loss reduction by magnetic perturbations at low pedestal density and collisionality in ASDEX upgrade

TitleParameter dependence of ELM loss reduction by magnetic perturbations at low pedestal density and collisionality in ASDEX upgrade
Publication TypeJournal Article
Year of Publication2017
AuthorsN. Leuthold, W. Suttrop, R. Fischer, A. Kappatou, A. Kirk, R. McDermott, A. Mlynek, M. Valovic, M. Willensdorfer
JournalPlasma Physics and Controlled Fusion
Volume59
Issue5
Pagination055004
Abstract

ELM mitigation by magnetic perturbations is studied at low pedestal collisionalities down to ITER-like values (V∗ e PED = 0.1) in ASDEX Upgrade. A comprehensive database of ELM energy losses for varying plasma density, heating power, edge safety factor and magnetic perturbation structure has been assembled to investigate parameter dependencies of ELM mitigation. It is found that magnetic perturbations with a toroidal mode number n = 2 can reduce the ELM energy loss normalized to the energy stored in the plasma pedestal from about 30% to less than 5%, i.e. by a factor of six, below an electron pedestal collisionality of V∗ e PED = 0.4. At this level of ELM mitigation a significant reduction of the pedestal pressure and, therefore, global plasma confinement occurs. This pedestal pressure reduction is mostly due to a reduction of plasma density, the so-called pump-out effect. Refueling by neutral beams and in particular by pellet injection is possible and can re-establish confinement, however, the ELM energy loss increases as well with increasing density. © 2017 Published by Elsevier B.V.

URLhttp://www.euro-fusionscipub.org/wp-content/uploads/eurofusion/WPMST1PR16_16203_submitted.pdf
DOI10.1088/1361-6587/aa5f70
Division

FP

Department

TP

PID3862f922771d62992bdb6a9a803c0b23
Alternate TitlePlasma Phys. Controlled Fusion
LabelOA

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