A Fokker–Planck Framework for Studying the Variability of the Magnetic Field Direction in the Alfvénic Streams of the Solar Wind

Turbulent rotations of the magnetic field vector are observed in the Alfvénic streams of the solar wind where the magnetic field strength remains close to a constant. They can lead to reversals of the radial magnetic field component or switchbacks. It is not ruled out from the data that the rotation...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2024-01, Vol.960 (2), p.L15
Main Authors: Bian, N. H., Li, Gang
Format: Article
Language:English
Subjects:
Field strength
Fluctuations
Interplanetary magnetic fields
Interplanetary turbulence
Magnetic fields
Magnetic properties
Probability distribution functions
Solar magnetic field
Solar wind
Stochastic processes
Streams
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Summary:Turbulent rotations of the magnetic field vector are observed in the Alfvénic streams of the solar wind where the magnetic field strength remains close to a constant. They can lead to reversals of the radial magnetic field component or switchbacks. It is not ruled out from the data that the rotations are divisible into the sum of small random angular deflections. In this work, we develop tools aimed at the analysis of the one-point statistical properties of the directional fluctuations of the magnetic field vector in the solar wind. The angular fluctuations are modeled by a drift-diffusion process which admits the exponential distribution as steady-state solution. Realizations of the stochastic process are obtained by solving the corresponding Langevin equation. It is shown that the cumulative effects of consecutive small-angle deflections can yield frequent reversals of the magnetic field vector even when the concentration parameter of the directional data is large. The majority of the rotations are associated with nearly transverse magnetic field fluctuations in this case.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ad17cc