Anisotropic phase-space cascades in 3D-3V hybrid-Vlasov-Maxwell simulations of plasma turbulence*

Elucidating the properties of turbulent fluctuations and how they are dissipated in weakly collisional plasmas is a fundamental step for understanding how turbulence feeds back on the macro-scale evolution of numerous space and astrophysical systems. In situ observations of the solar wind and the terrestrial magnetosheath have highlighted breaks in the turbulent spectra denoting a transition from the MHD inertial range to a kinetic range that arises at scales smaller than the proton gyroradius, as well as generation of structures in the particles distribution function.
In this talk we present an investigation of kinetic-range turbulence via 3D3V hybrid-Vlasov-Maxwell (fully-kinetic ions and fluid electrons) simulations with electron inertia[1]. In particular, we show the first evidence for a turbulent cascade of ion-entropy fluctuations involving the entire 6D phase-space in a simulation of electromagnetic turbulence: such a phase-space cascade is shown to be anisotropic with respect to the magnetic field in both real and velocity space and suggests that both linear and non-linear phase mixing are simultanously at work[2].
[1] Cerri, Servidio & Califano, ApJL 846, L18 (2017)
[2] Cerri, Kunz & Califano, ApJL 856, L13 (2018)