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P: Fachverband Plasmaphysik

P 10: Poster Session 2

P 10.12: Poster

Dienstag, 10. März 2020, 16:30–18:30, Empore Lichthof

Braginskii Transport Coefficients for the Gyrokinetic Sugama Collision Operator versus the full Landau Operator — •Mario Raeth and Klaus Hallatschek — Max Planck Institute of Plasma Physics, Garching, Germany

The ad-hoc model collision operator derived by Sugama et al. and implemented in a Eulerian gyrokinetic solver (CGYRO) is tested in detail against the multi-fluid transport equations for magnetised plasmas derived from the Landau collision operator by Braginskii . It has been shown that the anomalous transport levels in gyrokinetic turbulence simulations with this collision operator do not match Braginskii fluid levels in the presence of significant temperature fluctuations.
To further investigate the transport processes, scenarios are created which allow us to isolate the various transport processes described by the Braginskii fluid model. By this method, it is possible to see precisely which transport coefficients result from the Sugama operator. In addition to the deviation of the parallel transport processes of ∼20%, it is shown that the perpendicular heat flux is significantly larger (by ∼50% for the ion heat conductivity) than the quantities derived from the Landau operator. The ion stress caused by a sheared perpendicular heat flux is ten times larger than expected and the ion viscosity deviates by ∼ 40%. This indicates that the Sugama operator is not sufficiently accurate to achieve a close agreement between fluid and kinetic models, especially in the case of temperature perturbations in the plasma. Furthermore, ongoing work on the comparison with a full 6D kinetic model implemented by Kormann et al. will be presented.