Nonlinear phase mixing and phase-space cascade of entropy in gyrokinetic plasma turbulence.
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.
Tatsuno
T
T
Department of Physics, IREAP and CSCAMM, University of Maryland, College Park, Maryland 20742, USA.
Dorland
W
W
Schekochihin
A A
AA
Plunk
G G
GG
Barnes
M
M
Cowley
S C
SC
Howes
G G
GG