2018/02/28 by S. S. Cerri, Silvio Sergio Cerri, Matthew W. Kunz +2
Physics and Astronomy · #Anisotropy #Cascade #Computational physics #Gyrokinetics #Gyroradius #Ionosphere and magnetosphere dynamics #Magnetic confinement fusion research #Magnetic field #Magnetohydrodynamic turbulence #Magnetohydrodynamics #Mechanics #Phase space #Physics #Plasma #Quantum mechanics #Solar and Space Plasma Dynamics #Tokamak #Turbulence #astro-ph.SR #physics.plasm-ph #physics.space-ph
paper · pdf · doi:10.3847/2041-8213/aab557
version accepted in ApJL
arxiv created 2018/03/08 · openalex publication_date 2018/03/20 · arxiv updated 2018/04/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract To explain energy dissipation via turbulence in collisionless, magnetized plasmas, the existence of a dual real- and velocity-space cascade of ion-entropy fluctuations below the ion gyroradius has been proposed. Such a dual cascade, predicted by the gyrokinetic theory, has previously been observed in gyrokinetic simulations of two-dimensional, electrostatic turbulence. For the first time, we show evidence for a dual phase-space cascade of ion-entropy fluctuations in a three-dimensional simulation of hybrid-kinetic, electromagnetic turbulence. Some of the scalings observed in the energy spectra are consistent with a generalized theory for the cascade that accounts for the spectral anisotropy of critically balanced, intermittent, sub-ion-Larmor-scale fluctuations. The observed velocity-space cascade is also anisotropic with respect to the magnetic-field direction, with linear phase mixing along magnetic-field lines proceeding mainly at spatial scales above the ion gyroradius and nonlinear phase mixing across magnetic-field lines proceeding at perpendicular scales below the ion gyroradius. Such phase-space anisotropy could be sought in heliospheric and magnetospheric data of solar-wind turbulence and has far-reaching implications for the dissipation of turbulence in weakly collisional astrophysical plasmas.