Hannover 2010 – scientific programme

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P: Fachverband Plasmaphysik

P 5: Theory/Modelling I

P 5.5: Talk

Tuesday, March 9, 2010, 15:25–15:40, B 302

Transport bifurcations for zonal flows in 3D sheared slab drift wave systems — •Andreas Kammel and Klaus Hallatschek — Max-Planck-Institut für Plasmaphysik, Garching b. München, Germany

The Reynolds stress-governed interaction between drift waves and zonal flows in the highly nonlinear plasma edge is examined in detail using the turbulent two-fluid code NLET. Special focus is being placed on the structure of the flows.

Already in a simple 3-dimensional sheared slab cold-ion drift wave system based on the Hasegawa-Wakatani equations, transport bifurcations containing two different stable gradients have been found - a novelty for self-consistent first principles turbulence simulations. The density profiles develop corrugations (depending on one dimensionless parameter only) which represent stationary transport states with regions of steepened gradients and lowered diffusivity for the flows opposite to the electromagnetic drift direction. These 'negative' flows, which repulse the drift wave turbulence, become sharper and steeper than the 'positive' flows, yielding a flow asymmetry which can be understood by the introduction of a chemical potential.

In the future course of our studies, we plan to compare these drift wave zonal flows in the plasma edge to the geostrophic zonal flows in the atmospheres of gas giants. To this end, a new numerical code for the hydrodynamic, planetary case will be developed.