A review of relaxation and structure in some turbulent plasmas: magnetohydrodynamics and related models

Abstract

A brief overview is provided as an introduction to hydrodynamic-like turbulence that characterizes the dynamics of plasmas in several parameter regimes. This includes magnetohydrodynamics (MHD), the electron fluid plasma, which is closely related to two-dimensional hydrodynamics, and the solar wind, which is usually viewed as a laboratory for three-dimensional MHD, with more involved plasma physics at the dissipative scales. An emphasis is placed on energy decay, spectra, relaxation processes, coherent structures, and higher statistics with selected applications in solar wind and laboratory plasmas.

Keywords:

• magnetohydrodynamics
• solar wind
• turbulence theory
• intermittency
• relaxation
• plasma physics

Acknowledgments

[Acknowledgments] This research has been supported by the NSF SHINE program ATM-0752135, the Solar Terrestrial program AGS-1063439, and by NASA through the MMS mission NNX08AT76G, the Solar Probe Mission (ISIS subcontract, and the Heliophysics Theory program. W.H. Matthaeus is grateful for the hospitality of the University of Calabria, the assistance of Lorenzo Servidio, and the support for collaborators from the EU TURBOPLASMA program.

Notes

1. The unaveraged Alfvén timescale is (k·B ₀)⁻¹, where B ₀ is the mean magnetic field. This induces anisotropy [149] and the possibility of important additional time-scale effects. Here, we deal only with the isotropic case.