http://arxiv.org/abs/1510.02842
Plasma turbulence is ubiquitous in space and astrophysical plasmas, playing an important role in plasma energization, but the physical mechanisms that lead to dissipation of the turbulent energy remain to be definitively identified. This work addresses the fundamental physics of turbulent dissipation by examining the velocity-space structure that develops as a result of the collisionless interaction between the turbulent electromagnetic fluctuations and the particles in a low beta plasma. Both two- and three-dimensional (2D and 3D) nonlinear gyrokinetic simulations show an electron velocity-space signature qualitatively similar to that of the linear Landau damping of Alfv\’en waves in a 3D linear simulation. This evidence strongly suggests that the turbulent energy is transferred by Landau damping to electrons in low beta plasmas in both 2D and 3D, making possible the ultimate irreversible heating of the plasma. Although, in the 2D case with no variation along the equilibrium magnetic field, it may be expected that Landau damping is not possible, a common trigonometric correction factor appears in both the resonant denominator and the linear wave frequency, leading to an essentially unchanged resonance condition from the 3D case. Nonetheless, though the qualitative evolution of the 2D and 3D cases is similar, quantitatively the nonlinear energy transfer and subsequent dissipation is substantially slower in the 2D case.
T. Li, G. Howes, K. Klein, et. al.
Tue, 13 Oct 15
10/64
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