Speaker
Jorge Ferreira
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1057.pdf
Effects of electron cyclotron resonance heating
on toroidal Alfvén eigenmodes in tokamak plasmas
J. Ferreira1, F. Nabais1, P. Rodrigues1, R. Coelho1, A. Figueiredo1, M. Garcia-Munoz2,
T. Johnson3, P. Lauber4, S. E. Sharapov5, P. Vallejos3, M. A. Van Zeeland6, V. Bobkov4,
I.G.J. Classen7, M. Fitzgerald5, B. Geiger4, J. Galdon-Quiroga2, J. Gonzalez-Martin2,
L. Guimarãis1, M. Mantsinen8,9, V. Nikolaeva1, M. Rodriguez-Ramos2, L. Sanchís2,
P. A. Schneider4, A. Snicker10, and the AUG Team and the EUROfusion MST1 Teama
1
Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
2
Department of Atomic, Molecular and Nuclear Physics, Faculty of Physics, University of Seville, 41012 Seville, Spain
3
VR/Royal Institute of Technology KTH, Sweden
4
Max Planck Institute fur Plasmaphysik, Garching, Germany
5
CCFE, Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
6
General Atomics, PO Box 85608, San Diego, United States of America
7
FOM-Institute DIFFER, Nieuwegein, The Netherlands
8
Barcelona Supercomputing Center (BSC), Barcelona, Spain
9
ICREA, Barcelona, Spain
10
Aalto University, Aalto, Finland
A set of dedicated ASDEX-Upgrade experiments was recently carried out in order to
study the effects of localized electron cyclotron resonance heating (ECRH) on energetic-ion-
driven toroidal Alfvén eigenmodes (TAE). It was found that for discharges with a monotonic
profile of the safety factor, off-axis ECRH can make TAEs more unstable on timescales of a
few milliseconds while the effect of on-axis ICRH is much weaker [1].
To understand the mechanisms responsible for this effect, detailed calculations were performed
using the ideal MHD code MISHKA[2], and the recently upgraded hybrid MHD-drift-kinetic
code CASTOR-K [3, 4]. The distributions of the energetic ion populations accelerated by ion
cyclotron resonance heating (ICRH) were computed with the SELFO code [5]. A competition
between the mechanics that drive and damp the TAEs modes will be shown to be sufficient to
explain the observations.
To assess the stability of Alfvén eigenmodes different computer codes developed by different
groups have to be integrated. One problem that arises is how to exchange the full particle
distributions between them without appreciable loss of information. A new standard format to
exchange energetic particle distributions has been recently proposed[6], based on generalised
distribution functions in terms of the gyrocentre's constants of motion (energy, magnetic
moment, and toroidal canonical momentum), and has recently been adapted by a set of codes
such as ASCOT [7], CASTOR-K [3,4], HAGIS [8], and SELFO [5]. These recent upgrades
not only improve the quality and robustness of the code interfaces, but more importantly they
also increase the accuracy of the results.
[1] S.E. Sharapov et al., Plasma Phys. Control. Fusion 60 (2018) 014026
[2] A.B. Mikhailovskii et al., Plasma Phys. Rep. 23 (1997) 844
[3] D. Borba and W. Kener, J. Comput. Phys. 153 (1999) 101
[4] F. Nabais et al., Plasma Sci. Technol. 17 (2015) 89
[5] J. Hedin et al., Nuclear Fusion 42 (2002) 527
[6] M. Fitzgerald, P. Rodrigues, et al., to be published
[7] E. Hirvijoki, et al., Comp. Phys. Comm. 185 (1998)1310
[8] Pinches, S. D. et al., Comp. Phys. Comm. 111 (1998) 133
a
See the author list of H. Meyer et al., Nuclear Fusion 57 (2017) 102014.
