Magnetic reconnection and plasma transport in the presence of plasma turbulence
Abstract
Plasma turbulence can enhance the diffusion of both magnetic fields and plasmas. But, any theory must be consistent with their evolution equations having the mathematical form of advection-diffusion equations. Advection-diffusion equations have a remarkable feature. When the diffusion is extremely weak but non-zero, its magnitude makes only a small difference even when varied over sixteen orders of magnitude. Nevertheless, diffusion causes the solutions to differ fundamentally from those given by advection alone on a timescale that is only an order of magnitude longer than the timescale defined by the advective flow. This is true when the advective velocity is chaotic -- the exponential separation of neighboring streamlines -- as natural flows generally are. In addition to eddies, even highly turbulent flows can have large-scale coherent flows, which dominate their transport effects on the longest scales. \color{black} Basic physics and easily understood mathematics place important constraints, which are explained.
- Publication:
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arXiv e-prints
- Pub Date:
- August 2024
- DOI:
- 10.48550/arXiv.2408.00875
- arXiv:
- arXiv:2408.00875
- Bibcode:
- 2024arXiv240800875B
- Keywords:
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- Physics - Plasma Physics