Speaker
Mirko Wensing
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O4.107.pdf
SOLPS simulation of TCV divertor leg length studies
M. Wensing1 , H. De Oliveira1 , B. P. Duval1 , O. Février1 , A. Fil2 , R. Maurizio1 ,
H. Reimerdes1 , C. Theiler1 , C. K. Tsui1,3 K. Verhaegh1,2 , M. Wischmeier4 ,
the EUROfusion MST1 team and the TCV team
1 EPFL - Swiss Plasma Center (SPC), Lausanne, Switzerland
2 University of York - Plasma Institute, York, United Kingdom
3 University of California San Diego (UCSD), San Diego, United States
4 Max-Planck-Institut für Plasmaphysik, Garching, Germany
This contribution uses TCV experiments with varying divertor configurations to investigate the
particle and heat cross-field transport within the scrape-off layer, which greatly determines the
peak heat flux on the plasma-facing components. The proximity of expected peak heat fluxes to
the material limits for ITER raises the necessity of obtaining a quantitative understanding of the
mechanisms that determine the heat flux profiles on the divertor plates. Target heat flux profiles
are often described by a truncated exponential profile with a decay length λ convoluted with a
Gaussian of width S, which are interpreted as broadening due to diffusive transport upstream
and in the divertor regions, respectively [1].
The TCV tokamak with its 16 independent poloidal shaping coils provides unique capabilities
for studying the effect of divertor geometry on target heat flux profiles and large variations in
divertor leg length Ldiv , flux expansion and flux flaring have been achieved. It is, in particular,
found that an increase of Ldiv (~ factor 3.5) leads to a somewhat unexpected increase of λ , while
having little effect on S [2].
The aim of this study is to reproduce the experimental findings quantitatively using the
SOLPS code package. Sensitivity studies on spatially constant transport parameters were per-
formed to match an experimentally well-diagnosed case. It is shown that diffusive transport
without spatial dependence fails to reproduce the experimentally observed trends in λ and S, in
agreement with earlier studies [3]. Different setups of transport profiles are investigated: in the
first case the upstream cross-field transport increases as function of Ldiv , whereas in a second
approach the cross-field transport in the divertor is chosen to be radially asymmetric.
References
[1] T. Eich, et al., Phys. Rev. Lett. 107, 215001 (2011)
[2] R. Maurizio, et al., Nucl. Fusion 58, 016052 (2018)
[3] A. Gallo, et al., Plasma Phys. Control. Fusion 60, 014007 (2018)
