Speaker
Anton Jansen van Vuuren
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1101.pdf
Fast-ion transport study in the plasma periphery of ASDEX Upgrade
using fast-ion D-alpha spectroscopy
A. Jansen van Vuuren1 , B. Geiger1 , P.A. Schneider1 , A.S. Jacobsen1 , K. Mitosinkova2 ,
T. Lunt1 , J. Gonzalez-Martin3 and the ASDEX Upgrade and EUROfusion MST1 Teams1∗
1 Max-Planck Institute for Plasma Physics, Garching, Germany
2 Institute of Plasma Physics of the CAS, Prague, Czech Republic
3 Dept. of Mechanical and Manufacturing Engineering, University of Seville, Seville, Spain
Good confinement of fast ions in the plasma periphery is of particular importance for fusion
devices since these particles can easily be transported to unconfined orbits, become lost and
potentially damage first wall components. Several mechanisms exist that can redistribute fast
ions, of which the mode-induced transport might be the most critical one. However for a detailed
fast-ion transport analysis first, charge exchange (CX) losses and drifts in perturbed equilibria
must be considered.
Low density experiments were performed at ASDEX Upgrade with 5 MW of off-axis NBI
heating that show high fast-ion densities at the edge. During those experiments strong CX losses
were observed by a new edge fast-ion Dα (FIDA) diagnostic that measured intense signals
originating from CX reactions between fast ions and background neutrals. In order to model
this so called passive FIDA light first, the background neutral density is modelled with KN1D
and EMC3-EIRENE. The neutral density is then incorporated in TRANSP simulations which
include CX losses in the prediction of the fast-ion distribution. Finally the predicted fast-ion
and background neutral-density profiles are translated into synthetic passive FIDA spectra using
FIDASIM. When comparing measured and simulated spectra the best agreement is found for
high neutral densities that cause a reduction of up to 15% of the total fast-ion density. This
shows that CX losses can have a strong impact on the fast-ion density at the edge of ASDEX
Upgrade.
In addition, the experimental measurements show a clear modulation of the passive FIDA
signal during edge localised modes (ELMs) and after the application of RMPs. This is partly
explained by a modification of the background neutral density and possibly by fast-ion losses,
as observed using the fast-ion loss detectors [1]. Detailed modelling results will be presented,
including ELM resolved simulations and predictions of the 3D perturbations induced by RMPs.
References
[1] M. García-Muñoz et al, Plasma Phys. Control. Fusion 55, 12 (2013)
∗
See H. Meyer et al, Nucl. Fusion 57 102014 (2017)
