Abstract
Abstract
We explore the multifaceted important features of turbulence (e.g., anisotropy, dispersion, and diffusion) in the three-dimensional (3D) wavenumber domain (k
∥, k
⊥,1, k
⊥,2), by employing the k-filtering technique to high-quality measurements of fields and particles from the Magnetospheric Multiscale Mission (MMS) multi-spacecraft constellation. We compute the 3D power spectral densities (PSDs) of magnetic and electric field fluctuations (marked as PSD(δ
B
(
k
)) and
PSD
(
δ
E
〈
v
i
〉
′
(
k
)
)
, respectively), both of which show a prominent spectral anisotropy in the sub-ion range. We give the first 3D image of the bifurcation between the power spectra of the electric and magnetic fluctuations, by calculating the ratio between
PSD
(
δ
E
〈
v
i
〉
′
(
k
)
)
and PSD(δ
B
(
k
)), the distribution of which is related to the nonlinear dispersion relation. We also compute the ratio between electric spectra in different reference frames defined by the ion bulk velocity,
PSD
(
δ
E
local
v
i
′
)
/
PSD
(
δ
E
〈
v
i
〉
′
)
, to visualize the turbulent ion diffusion region (T-IDR) in wavenumber space. The T-IDR has an anisotropy and a preferential direction of wavevectors, which is generally consistent with the plasma wave theory prediction based on the dominance of kinetic Alfvén waves. This work demonstrates the worth of the k-filtering technique in diagnosing turbulence comprehensively, especially when the electric field is involved.
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
3 articles.
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