Kinetic simulations of the interruption of large-amplitude shear-Alfvén waves in a high-beta plasma

Abstract

Using two-dimensional hybrid-kinetic simulations, we explore the nonlinear "interruption" of standing and traveling shear-Alfvén waves in collisionless plasmas. Interruption involves a self-generated pressure anisotropy removing the restoring force of a linearly polarized Alfvénic perturbation, and occurs for wave amplitudes $\delta B_{\perp }/B_0\gtrsim {\beta }^{-1/2}$ (where $\beta$ is the ratio of thermal to magnetic pressure). We use highly elongated domains to obtain maximal scale separation between the wave and the ion gyroscale. For standing waves above the amplitude limit, we find that the large-scale magnetic field of the wave decays rapidly. The dynamics are strongly affected by the excitation of oblique firehose modes, which transition into long-lived parallel fluctuations at the ion gyroscale and cause significant particle scattering. Traveling waves are damped more slowly, but are also influenced by small-scale parallel fluctuations created by the decay of firehose modes. Our results demonstrate that collisionless plasmas cannot support linearly polarized Alfvén waves above $\delta B_{\perp }/B_0\sim {\beta }^{-1/2}$. They also provide a vivid illustration of two key aspects of low-collisionality plasma dynamics: (i) the importance of velocity-space instabilities in regulating plasma dynamics at high $\beta$, and (ii) how nonlinear collisionless processes can transfer mechanical energy directly from the largest scales into thermal energy and microscale fluctuations, without the need for a scale-by-scale turbulent cascade.

References in corpus (22)

• Astrophysical gyrokinetics: kinetic and fluid turbulent cascades in magnetized weakly collisional plasmas
• Spectrum of magnetohydrodynamic turbulence
• X-ray Spectroscopy of Cooling Clusters
• Magnetic fluctuation power near proton temperature anisotropy instability thresholds in the solar wind
• Turbulent Heating in Galaxy Clusters Brightest in X-rays
• Recent progress in astrophysical plasma turbulence from solar wind observations
• Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
• Particle Heating by Alfvenic Turbulence in Hot Accretion Flows
• Shearing Box Simulations of the MRI in a Collisionless Plasma
• A thermally stable heating mechanism for the intracluster medium: turbulence, magnetic fields and plasma instabilities
• Magnetic turbulence in cool cores of galaxy clusters
• Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence
• Nonlinear growth of firehose and mirror fluctuations in turbulent galaxy-cluster plasmas
• A statistical model of three-dimensional anisotropy and intermittency in strong Alfvénic turbulence
• Pegasus: A New Hybrid-Kinetic Particle-in-Cell Code for Astrophysical Plasma Dynamics
• A nonlinear theory of the parallel firehose and gyrothermal instabilities in a weakly collisional plasma
• PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction
• Pressure-anisotropy-driven microturbulence and magnetic-field evolution in shearing, collisionless plasma
• Nonlinear mirror instability
• A stringent limit on the amplitude of Alfvénic perturbations in high-beta low-collisionality plasmas
• Lecture notes: Astrophysical fluid dynamics
• Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas

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