NBI-driven Alfvenic modes at ASDEX Upgrade

TitleNBI-driven Alfvenic modes at ASDEX Upgrade
Publication TypeJournal Article
Year of Publication2012
AuthorsP. Lauber, I.G.J. Classen, D. Curran, V. Igochine, B. Geiger, S. da Graca, M. García-Muñoz, M. Maraschek, P. McCarthy
JournalNuclear Fusion
Volume52
Issue9
Pagination094007
Date PublishedSep
Type of ArticleArticle; Proceedings Paper
ISBN Number0029-5515
KeywordsEXPLANATION, MHD SPECTROSCOPY, N=0 CHIRPING MODE, STABILITY, TOKAMAKS
Abstract

A large variety of electromagnetic modes excited by NBI-generated energetic ions are observed in the early phase of many discharges at ASDEX Upgrade. In addition to the well-known reversed shear Alfven eigenmodes (RSAE) and the toroidal Alfven eigenmodes (TAE), a set of modes around 70 kHz is observed as recently described in [7]. The modes were identified to be beta-induced Alfven eigenmodes (BAE) connected with the appearance of the q = 2 and the q = 1.5 surface during the current ramp-up phase. In the view of ITER, these BAEs may occur in scenarios with q approximate to 2 (scenario 4) and therefore add significantly to the transport of energetic ions due to RSAEs and TAEs. Experimentally, the combination of ECE, soft-x-ray and magnetic measurements allows for a very reliable mode position and mode structure determination. The measurements are compared with linear gyrokinetic calculations employing the LIGKA code that uses a fully kinetic model to describe fast-particle-driven modes in general tokamak geometry.

DOI10.1088/0029-5515/52/9/094007
Division

FP

Department

PDG

PID

1ae53396d42108b291ab31066da8bb69

Alternate TitleNucl. Fusion

Go back one page.