Plasma turbulence at ion scales: a comparison between PIC and Eulerian hybrid-kinetic approaches

Abstract

Kinetic-range turbulence in magnetized plasmas and, in particular, in the context of solar-wind turbulence has been extensively investigated over the past decades via numerical simulations. Among others, one of the widely adopted reduced plasma model is the so-called hybrid-kinetic model, where the ions are fully kinetic and the electrons are treated as a neutralizing (inertial or massless) fluid. Within the same model, different numerical methods and/or approaches to turbulence development have been employed. In the present work, we present a comparison between two-dimensional hybrid-kinetic simulations of plasma turbulence obtained with two complementary approaches spanning about two decades in wavenumber - from MHD inertial range to scales well below the ion gyroradius - with a state-of-the-art accuracy. One approach employs hybrid particle-in-cell (HPIC) simulations of freely-decaying Alfvénic turbulence, whereas the other consists of Eulerian hybrid Vlasov-Maxwell (HVM) simulations of turbulence continuously driven with partially-compressible large-scale fluctuations. Despite the completely different initialization and injection/drive at large scales, the same properties of turbulent fluctuations at $k_{\perp }{\rho }_i\gtrsim 1$ are observed. The system indeed self-consistently "reprocesses" the turbulent fluctuations while they are cascading towards smaller and smaller scales, in a way which actually depends on the plasma beta parameter. Small-scale turbulence has been found to be mainly populated by kinetic Alfvén wave (KAW) fluctuations for $\beta \ge 1$, whereas KAW fluctuations are only sub-dominant for low-$\beta$.

18 pages, 4 figures, accepted for publication in J. Plasma Phys. (Collection: "The Vlasov equation: from space to laboratory plasma physics")

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• High-resolution hybrid simulations of kinetic plasma turbulence at proton scales
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• Von Karman-Howarth equation for Hall magnetohydrodynamics: Hybrid simulations
• Fully kinetic versus reduced-kinetic modelling of collisionless plasma turbulence
• Dependence of Kinetic Plasma Turbulence on Plasma beta
• Astrophysical gyrokinetics: Turbulence in pressure-anisotropic plasmas at ion scales and beyond
• Kinetic plasma turbulence: recent insights and open questions from 3D3V simulations
• On stochastic heating and its phase-space signatures in low-$\beta$ kinetic turbulence
• Turbulent electromagnetic fields at sub-proton scales: two-fluid and full-kinetic plasma simulations
• Three-dimensional magnetic reconnection in particle-in-cell simulations of anisotropic plasma turbulence
• Three-dimensional simulations of solar wind turbulence with the hybrid code CAMELIA
• Fluid simulations of plasma turbulence at ion scales: comparison with Vlasov-Maxwell simulations
• Modeling Kelvin-Helmholtz instability-driven turbulence with hybrid simulations of Alfvénic turbulence
• Nonlinear Reconnection in Magnetized Turbulence
• Bridging hybrid- and full-kinetic models with Landau-fluid electrons: I. 2D magnetic reconnection
• Characterizing current structures in 3D hybrid-kinetic simulations of plasma turbulence
• Local and global properties of energy transfer in models of plasma turbulence
• Finite-Larmor-radius equilibrium and currents of the Earth's flank magnetopause
• A Hybrid Gyrokinetic Ion and Isothermal Electron Fluid Code for Astrophysical Plasma
• Large-scale Control of Kinetic Dissipation in the Solar Wind
• Identification and characterization of current sheets in collisionless plasma turbulence