Speaker
Klara Mitosinkova
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1100.pdf
Direct determination of background neutral density profiles from neutral
particle analyzers
K. Mitosinkova1,2 , B. Geiger3 , P. A. Schneider3 , A. van Vuuren3 , A. N. Karpushov4 ,
the ASDEX Upgrade team5 , the TCV team6 and the EUROfusion MST1 team7
1 Institute of Plasma Physics of the CAS, Prague, Czech Republic
2 Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
3 Max-Planck Institute für Plasmaphysik, Garching, Germany
4 Swiss Plasma Center, EPFL, Lausanne, Switzerland
5 See author list of A. Kallenbach et al 2017 Nucl. Fusion 57 102015
6 See author list of S Coda et al 2017 Nucl. Fusion 57 102011
7 See author list of H Meyer et al 2017 Nucl. Fusion 57 102014
Profiles of the background neutral density, n0 , are important for plasma transport understanding
because n0 is responsible for charge-exchange losses, as well as, for plasma fuelling. However,
detailed n0 profiles are not routinely available at most fusion devices.
Here we present a fast reconstruction of n0 , directly from neutral particle analyzer (NPA)
data, which has become possible thanks to the steady improvement of ion temperature and ion
density measurements. NPAs measure energy resolved fluxes of neutrals escaping the plasma,
Γ(En ), formed by charge-exchange collisions between the plasma ions and the background
neutrals. Calculated fluxes Γ(En ), based on knowledge of the other plasma parameters, are
fitted to measured ones by optimizing n0 profile parameters.
The method is successfully benchmarked by comparing the actual NPA measurements with
synthetic NPA fluxes from FIDASIM simulation with calculated n0 used as the input. In addition
the reconstructed n0 profiles are compared with predictions from KN1D, TRANSP/FRANTIC
and DOUBLE.
As a fist application of the n0 profiles obtained from the new direct analysis, ELM-resolved
neutral densities will be presented. Moreover, the impact of the inferred neutral densities on the
level of charge-exchange losses will be discussed for ASDEX Upgrade and TCV cases.
