Nonlinear interactions in spherically polarized Alfvénic turbulence
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Turbulent magnetic field fluctuations observed in the solar wind often maintain a constant-magnitude magnetic field accompanied by spherically polarized velocity fluctuations; these signatures are characteristic of large-amplitude Alfvén waves. Nonlinear energy transfer in Alfvénic turbulence is typically considered in the small-amplitude limit where the constant-magnitude condition may be neglected; in contrast, nonlinear energy transfer of large-amplitude fluctuations remains relatively unstudied. We develop a method to analyze large-amplitude turbulence through studying fluctuations as constant-magnitude rotations in the de Hoffmann–Teller frame, in which the convected electric field of the fluctuations vanishes such that the frame and fluctuations are copropagating. Our analysis reveals signatures of large-amplitude effects deep into the inertial range. While the dominant fluctuations are consistent with spherically polarized large-amplitude Alfvén waves, the subdominant fluctuations are relatively compressible. Signatures of nonlinear interaction between the large-amplitude spherically polarized mode with the subdominant population reveal highly aligned transverse components. In many theoretical models of Alfvénic turbulence, alignment is thought to reduce nonlinearity; our observations suggest that the observed alignment is sufficient to either reduce shear nonlinearity such that non-Alfvénic interactions may be responsible for energy transfer in spherically polarized states, or alternatively that counterpropagating fluctuations maintain anomalous coherence, a predicted signature of reflection-driven turbulence.
Date Issued
2025-05-20
Date Acceptance
2025-03-24
Citation
The Astrophysical Journal (ApJ), 2025, 985 (1)
ISSN
0004-637X
Publisher
IOP Publishing
Journal / Book Title
The Astrophysical Journal (ApJ)
Volume
985
Issue
1
Copyright Statement
© 2025. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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Subjects
AMPLITUDE ALFVEN WAVES
Astronomy & Astrophysics
CRITICAL BALANCE
EVOLUTION
INNER HELIOSPHERE
MAGNETIC-FIELD FLUCTUATIONS
PARKER SOLAR PROBE
Physical Sciences
REFLECTION-DRIVEN
RESIDUAL ENERGY
Science & Technology
SUN
WIND DRIVEN
Publication Status
Published
Article Number
49
Date Publish Online
2025-05-14