Identification of the weak-to-strong transition in Alfvénic turbulence from space plasma

Abstract

Plasma turbulence is a ubiquitous dynamical process that transfers energy across many spatial and temporal scales in astrophysical and space plasma systems. Although the theory of anisotropic magnetohydrodynamic (MHD) turbulence has successfully described phenomena in nature, its core prediction of an Alfvenic transition from weak to strong MHD turbulence when energy cascades from large to small scales has not been observationally confirmed. Here we report the first observational evidence for the Alfvenic weak-to-strong transition in MHD turbulence in the terrestrial magnetosheath using the four Cluster spacecraft. The observed transition indicates the universal existence of strong turbulence regardless of the initial level of MHD fluctuations. Moreover, the observations demonstrate that the nonlinear interactions of MHD turbulence play a crucial role in the energy cascade, widening the directions of the energy cascade and broadening the fluctuating frequencies. Our work takes a critical step toward understanding the complete picture of turbulence cascade, connecting the weak and strong MHD turbulence systems. It will have broad implications in star formation, energetic particle transport, turbulent dynamo, and solar corona or solar wind heating.

submitted; 24 pages; 4 figures

References in corpus (7)

• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Compressible Turbulence in Galaxy Clusters: Physics and Stochastic Particle Re-acceleration
• Cosmic Ray Propagation: Nonlinear Diffusion Parallel and Perpendicular to Mean Magnetic Field
• Shattering and coagulation of dust grains in interstellar turbulence
• Nature of the MHD and kinetic scale turbulence in the magnetosheath of Saturn: Cassini observations
• Analysis of Magnetohydrodynamic Perturbations in Radial-field Solar Wind from Parker Solar Probe Observations
• Multi-spacecraft Analysis of the Properties of Magnetohydrodynamic Fluctuations in Sub-Alfvénic Solar Wind Turbulence at 1 AU

Cited by in corpus (4)

• On the scaling and anisotropy of two subranges in the inertial range of solar wind turbulence
• Observations of Turbulence and Particle Transport at Interplanetary Shocks: Transition of Transport Regimes
• Diagnosing Interstellar Magnetic Turbulence with TeV Pulsar Halos
• Introduction to Strong Alfvénic MHD Turbulence