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arXiv · 0811.2538

Nonlinear phase mixing and phase-space cascade of entropy in gyrokinetic plasma turbulence

T. Tatsuno·W. Dorland·A. A. Schekochihin·G. G. Plunk·M. Barnes·S. C. Cowley·G. G. Howes
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Abstract

Electrostatic turbulence in weakly collisional, magnetized plasma can be interpreted as a cascade of entropy in phase space, which is proposed as a universal mechanism for dissipation of energy in magnetized plasma turbulence. When the nonlinear decorrelation time at the scale of the thermal Larmor radius is shorter than the collision time, a broad spectrum of fluctuations at sub-Larmor scales is numerically found in velocity and position space, with theoretically predicted scalings. The results are important because they identify what is probably a universal Kolmogorov-like regime for kinetic turbulence; and because any physical process that produces fluctuations of the gyrophase-independent part of the distribution function may, via the entropy cascade, result in turbulent heating at a rate that increases with the fluctuation amplitude, but is independent of the collision frequency.

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T. Tatsuno, W. Dorland, A. A. Schekochihin, G. G. Plunk, M. Barnes, S. C. Cowley, G. G. Howes. 2008-11-16. Nonlinear phase mixing and phase-space cascade of entropy in gyrokinetic plasma turbulence. https://doi.org/10.1103/physrevlett.103.015003

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