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arXiv · 1405.5375

Collision-dependent power law scalings in 2D gyrokinetic turbulence

S. S. Cerri·A. Bañón Navarro·F. Jenko·D. Told
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Abstract

Nonlinear gyrokinetics provides a suitable framework to describe short-wavelength turbulence in magnetized laboratory and astrophysical plasmas. In the electrostatic limit, this system is known to exhibit a free energy cascade towards small scales in (perpendicular) real and/or velocity space. The dissipation of free energy is always due to collisions (no matter how weak the collisionality), but may be spread out across a wide range of scales. Here, we focus on freely-decaying 2D electrostatic turbulence on sub-ion-gyroradius scales. An existing scaling theory for the turbulent cascade in the weakly collisional limit is generalized to the moderately collisional regime. In this context, non-universal power law scalings due to multiscale dissipation are predicted, and this prediction is confirmed by means of direct numerical simulations.

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S. S. Cerri, A. Bañón Navarro, F. Jenko, D. Told. 2014-07-24. Collision-dependent power law scalings in 2D gyrokinetic turbulence. https://doi.org/10.1063/1.4892347

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