Erlangen 2018 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 1: Helmholtz Graduate School I - Theory
P 1.2: Vortrag
Montag, 5. März 2018, 10:55–11:20, A 0.112
Gyro-kinetic simulations of tokamaks and stellarators including collisions — •Christoph Slaby, Axel Könies, and Ralf Kleiber — Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald
Gyro-kinetic particle-in-cell simulations are a versatile numerical tool that we use to compute the non-linear dynamics of energetic-ion-driven Alfvénic perturbations. Collisions, though often neglected in numerical simulations, play an important role, since they can significantly modify the non-linear saturation levels and thus influence particle transport out of the plasma. Especially with regard to a future fusion reactor, gaining an understanding of the underlying physics is crucial.
The non-linear dynamics and saturation of toroidicity-induced Alfvén eigenmodes is studied in tokamak and Wendelstein 7-X (W7-X) geometry. In the tokamak case, the numerical findings agree with the analytically predicted ν2/3-scaling from the Berk-Breizman model. On the other hand, the stellarator W7-X which is not covered by analytical theory shows a different scaling.
Lastly, hybrid simulations are performed for a realistic W7-X scenario looking for unstable modes that could be experimentally relevant. This W7-X case includes neutral beam injection, as foreseen for the up-coming operation phase 1.2b, and a realistic slowing-down distribution function for the fast ions coupled with a slowing-down collision operator.