Investigation of fast particle driven instabilities by 2D electron cyclotron emission imaging on ASDEX Upgrade

TitleInvestigation of fast particle driven instabilities by 2D electron cyclotron emission imaging on ASDEX Upgrade
Publication TypeJournal Article
Year of Publication2011
AuthorsI.G.J. Classen, P. Lauber, D. Curran, J.E Boom, B.J Tobias, C.W. Domier, NC Luhmann, Jr., H.K Park, M.G Munoz, B. Geiger, M. Maraschek, M.A VanZeeland, S. da Graca
JournalPlasma Physics and Controlled Fusion
Volume53
Issue12
Pagination124018
Date PublishedDec
Type of ArticleArticle
ISBN Number0741-3335
KeywordsALFVEN MODES, CASCADES, EIGENMODES, STABILITY, TOKAMAK
Abstract

Detailed measurements of the 2D mode structure of Alfven instabilities in the current ramp-up phase of neutral beam heated discharges were performed on ASDEX Upgrade, using the electron cyclotron emission imaging (ECEI) diagnostic. This paper focuses on the observation of reversed shear Alfven-eigenmodes (RSAEs) and bursting modes that, with the use of the information from ECEI, have been identified as beta-induced Alfven eigenmodes (BAEs). Both RSAEs with first and second radial harmonic mode structures were observed. Calculations with the linear gyro-kinetic code LIGKA revealed that the ratio of the damping rates and the frequency difference between the first and second harmonic modes strongly depended on the shape of the q-profile. The bursting character of the BAE type modes, which were radially localized to rational q surfaces, was observed to sensitively depend on the plasma parameters, ranging from strongly bursting to almost steady state.

DOI10.1088/0741-3335/53/12/124018
Division

FP

Department

PDG

PID

32afd99893443c77ea31d2a8a80d4e3d

Alternate TitlePlasma Phys. Control. Fusion

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