Journal Article

FZJ-2017-05056

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png The role of the density profile in the ASDEX-Upgrade pedestal structure

Dunne, M. G. (Corresponding author) ; Potzel, S. ; Reimold, F. (Corresponding author)FZJ* ; Wischmeier, M. ; Wolfrum, E. ; Frassinetti, L. ; Beurskens, M. ; Bilkova, P. ; Cavedon, M. ; Fischer, R. ; Kurzan, B. ; Laggner, F. M. ; McDermott, R. M. ; Tardini, G. ; Trier, E. ; Viezzer, E. ; Willensdorfer, M.

2017
IOP Publ. Bristol

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Please use a persistent id in citations: http://hdl.handle.net/2128/14987  doi:10.1088/0741-3335/59/1/014017

Abstract: Experimental evidence for the impact of a region of high density localised in the high-field side scrape-off layer (the HFSHD) on plasma confinement is shown in various dedicated experiments on ASDEX Upgrade (AUG). Increasing main ion fuelling is shown to increase the separatrix density and shift the density profile outwards. Predictive pedestal modelling of this shift indicates a 25% decrease in the attainable pedestal top pressure, which compares well with experimental observations in the gas scan.Since the HFSHD can be mitigated by applying nitrogen seeding, a combined scan in fuelling rate, heating power, and nitrogen seeding is presented. Significant increases in the achievable pedestal top pressure are observed with seeding, in particular at high heating powers, and are correlated with inward shifted density profiles and a reduction of the HFSHD and separatrix density. Interpretive linear stability analysis also confirms the impact of a radially shifted pressure profile on peeling-ballooning stability, with an inward shift allowing access to higher pressure gradients and pedestal widths.

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Contributing Institute(s):

1. Plasmaphysik (IEK-4)

Research Program(s):

1. 174 - Plasma-Wall-Interaction (POF3-174) (POF3-174)
2. EUROfusion - Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium (633053) (633053)

Appears in the scientific report 2017

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Database coverage:
; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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