Speaker
Dirk Reiser
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1024.pdf
Langevin approach for plasma-surface interaction:
turbulent sputtering and surface morphology
D. Reiser
Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik,
52425 Jülich, Germany
The eminent role of plasma instabilities and related turbulent effects in fusion research is
well known. Prominent examples relevant for future experiments and reactor operation are the
anomalous transport degrading confinement properties and the Edge Localized Modes (ELM’s)
leading to intermittent expulsion of particles and heat onto the divertor plates.
However, an integrated simulation taking into account the temporal evolution of the multi-scale
plasma dynamics and the interaction of the plasma with plasma-facing components is currently
not within reach due to limitations in computational resources.
On the other hand, if the focus of research is not that much on the detailed origin of the plasma
turbulence but rather on the interaction with material boundaries, a half-empirical approach is
available via the use of so-called synthetic turbulence models. Such models can be employed
to mimic the basic statistical features of the plasma dynamics known from more detailed sim-
ulations and/or from experiment. With the knowledge of spatiotemporal correlations and am-
plitudes the plasma turbulence can be parametrized and its time evolution can be modelled by
means of fast algorithms. This approach has been successfully adopted already for the analy-
sis of plasma-wall interaction in linear devices [1]. The extension to tokamak geometries is
straightforward and might be applied to the studies of impurity transport in the presence of
ELM’s. Moreover, this approach can be extended consistently by implementing additionally
a Bradley-Harper-like model [2] for the morphological changes in the plasma-facing material,
which is based on similar numerical methods like the generation of synthetic plasma turbulence.
In this work we present a Langevin computational model for the linear device PSI-2 [3, 4] based
on this combination of plasma turbulence with impurity sputtering and morphological changes
of the target material. Scans through relevant parameter ranges of PSI-2 operational conditions
are presented.
References
[1] D. Reiser et al., Phys. Scr. 2017, 014039 (2017).
[2] V. O. Kharchenko and D. O. Kharchenko, Condensed Matter Physics 14, 23602 (2011).
[3] A. Kreter et al., Fusion Sci. Technol. 68 (1), 8-14 (2015).
[4] A. Kreter, Fusion Sci. Technol. 59 (1), 51-56 T (2011).
