The Development of Magnetic Field Line Wander by Plasma Turbulence

Abstract

Plasma turbulence occurs ubiquitously in space and astrophysical plasmas, mediating the nonlinear transfer of energy from large-scale electromagnetic fields and plasma flows to small scales at which the energy may be ultimately converted to plasma heat. But plasma turbulence also generically leads to a tangling of the magnetic field that threads through the plasma. The resulting wander of the magnetic field lines may significantly impact a number of important physical processes, including the propagation of cosmic rays and energetic particles, confinement in magnetic fusion devices, and the fundamental processes of turbulence, magnetic reconnection, and particle acceleration. The various potential impacts of magnetic field line wander are reviewed in detail, and a number of important theoretical considerations are identified that may influence the development and saturation of magnetic field line wander in astrophysical plasma turbulence. The results of nonlinear gyrokinetic simulations of kinetic Alfven wave turbulence of sub-ion length scales are evaluated to understand the development and saturation of the turbulent magnetic energy spectrum and of the magnetic field line wander. It is found that turbulent space and astrophysical plasmas are generally expected to contain a stochastic magnetic field due to the tangling of the field by strong plasma turbulence. Future work will explore how the saturated magnetic field line wander varies as a function of the amplitude of the plasma turbulence and the ratio of the thermal to magnetic pressure, known as the plasma beta.

28 pages, 9 figures, accepted for publication in Journal of Plasma Physics

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Cited by in corpus (6)

• Laboratory Space Physics: Investigating the Physics of Space Plasmas in the Laboratory
• Kinetic Turbulence in Astrophysical Plasmas: Waves and/or Structures?
• Nonlinear energy transfer and current sheet development in localized Alfven wavepacket collisions in the strong turbulence limit
• The density distribution and physical origins of intermittency in supersonic, highly magnetised turbulence with diverse modes of driving
• The Alfvenic nature of energy transfer mediation in localized, strongly nonlinear Alfven wavepacket collisions
• Statistical Study and Live Catalogue of Multi-Spacecraft 3He-Rich Time Periods over Solar Cycles 23, 24, and 25