Fast-ion transport induced by Alfven eigenmodes in the ASDEX Upgrade tokamak

TitleFast-ion transport induced by Alfven eigenmodes in the ASDEX Upgrade tokamak
Publication TypeJournal Article
Year of Publication2011
AuthorsM. García-Muñoz, I.G.J. Classen, B. Geiger, W.W Heidbrink, M.A VanZeeland, S. Akaslompolo, R. Bilato, V. Bobkov, M. Brambilla, G.D Conway, S. da Graca, V. Igochine, P. Lauber, N. Luhmann, M. Maraschek, F. Meo, H. Park, M. Schneller, G. Tardini
JournalNuclear Fusion
Volume51
Issue10
Pagination103013
Date PublishedOct
Type of ArticleArticle
ISBN Number0029-5515
KeywordsBEAM, DIII-D, FUSION PRODUCTS, INSTABILITIES, JET, PHYSICS, PLASMAS, SCINTILLATOR PROBE, STELLARATOR, TFTR
Abstract

A comprehensive suite of diagnostics has allowed detailed measurements of the Alfven eigenmode (AE) spatial structure and subsequent fast-ion transport in the ASDEX Upgrade (AUG) tokamak [ 1]. Reversed shear Alfven eigenmodes (RSAEs) and toroidal induced Alfven eigenmodes (TAEs) have been driven unstable by fast ions from ICRH as well as NBI origin. In ICRF heated plasmas, diffusive and convective fast-ion losses induced by AEs have been characterized in fast-ion phase space. While single RSAEs and TAEs eject resonant fast ions in a convective process directly proportional to the fluctuation amplitude, delta B/B, the overlapping of multiple RSAE and TAE spatial structures and wave-particle resonances leads to a large diffusive loss, scaling as (delta B/B)(2). In beam heated discharges, coherent fast-ion losses have been observed primarily due to TAEs. Core localized, low amplitude NBI driven RSAEs have not been observed to cause significant coherent fast-ion losses. The temporal evolution of the confined fast-ion profile in the presence of RSAEs and TAEs has been monitored with high spatial and temporal resolution. A large drop in the central fast-ion density due to many RSAEs has been observed as q(min) passes through an integer. The AE radial and poloidal structures have been obtained with unprecedented details using a fast SXR as well as 1D and 2D ECE radiometers. GOURDON and HAGIS simulations have been performed to identify the orbit topology of the escaping ions and study the transport mechanisms. Both passing and trapped ions are strongly redistributed by AEs.

DOI10.1088/0029-5515/51/10/103013
Division

FP

Department

PDG

PID

99af23813259e2ea3e780644e8d3b410

Alternate TitleNucl. Fusion

Go back one page.