Fast-Ion Losses due to High-Frequency MHD Perturbations in the ASDEX Upgrade Tokamak

M. García-Muñoz, H.-U. Fahrbach, S. Günter, V. Igochine, M. J. Mantsinen, M. Maraschek, P. Martin, P. Piovesan, K. Sassenberg, and H. Zohm

Phys. Rev. Lett. 100, 055005 – Published 6 February 2008

Abstract

Time-resolved energy and pitch angle measurements of fast-ion losses correlated in frequency and phase with high-frequency magnetohydrodynamic perturbations have been obtained for the first time in a magnetic fusion device and are presented here. A detailed analysis of fast-ion losses due to toroidal Alfvén eigenmodes has revealed the existence of a new core-localized magnetohydrodynamic perturbation, the sierpes mode. The sierpes mode is a non-Alfvénic instability which dominates the losses of fast ions in ion cyclotron resonance heated discharges, and it is named for its footprint in the spectrograms (“sierpes” means “snake” in Spanish). The sierpes mode has been reconstructed by means of highly resolved multichord soft-x-ray measurements.

Received 24 June 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.055005

Authors & Affiliations

M. García-Muñoz^1,*, H.-U. Fahrbach¹, S. Günter¹, V. Igochine¹, M. J. Mantsinen^1,4, M. Maraschek¹, P. Martin^2,3, P. Piovesan^2,3, K. Sassenberg^1,5, and H. Zohm¹

¹Max-Planck-Institut für Plasmaphysik, EURATOM Association Boltzmannstrasse 2, D-85748 Garching, Germany
²Consorzio RFX, Associazione EURATOM-ENEA per la fusione, Padova, Italy
³Physics Department, University of Padova, Italy
⁴Helsinki University of Technology, Association Euratom-Tekes, P.O. Box 4100, FIN-02015 HUT, Finland
⁵University College Cork, Association EURATOM-DCU, Cork, Ireland

^*Manuel.Garcia-Munoz@ipp.mpg.de

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Vol. 100, Iss. 5 — 8 February 2008

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