In this section
@article{Ergun:2026:1538-4357/ae53d8,
author = {Ergun, RE and Vo, T and Qi, Y and Chasapis, A and Pathak, N and Usanova, ME and Ahmadi, N and George, H and Schwartz, SJ},
doi = {1538-4357/ae53d8},
journal = {Astrophysical Journal},
title = {Evidence of a Subkinetic Spectral Break in a Strongly Turbulent Collisionless Plasma},
url = {http://dx.doi.org/10.3847/1538-4357/ae53d8},
volume = {1001},
year = {2026}
}
TY - JOUR
AB - We investigate the magnetic (B) and electric (E) field spectra in the dissipation range of strong turbulence of a collisionless plasma. This investigation, which is relevant to turbulence studies in many astrophysical settings, is enabled by high-resolution measurements from the four-spacecraft Magnetospheric Multiscale (MMS) mission in the Earth’s magnetotail. B and E spectra are derived as a function of the product of the wave number and electron skin depth (|k| d<inf>e</inf>) using a novel technique that employs time-delay analysis on multiple intervals of B and E. Using the MMS tetrahedral formation with close (several d<inf>e </inf>) spacing, velocities of B and E signals can be derived so that native frequency-based spectra can be accurately translated to k spectra. The most important finding is a mathematically significant break in the B spectral index that appears at |k| d<inf>e</inf> ≈ 1. In the subion range, which spans from the ion inertial length (d<inf>ι </inf>) to d<inf>e </inf>, the B spectral index is −2.35, then steepens to − 3.13 at sub-d<inf>e </inf> scales. As expected from previously derived frequency spectra, E has a particularly shallow spectral index (−0.67) in the subion range. At scales smaller than d<inf>e </inf> and/or the electron thermal gyroradius (ρ<inf>e </inf>), the E spectral index steepens to −2.73. Spectral breaks in both B and E in the dissipation range indicate a change in the physical dissipation processes from ion to electron domination at |k| d<inf>e</inf> ≈ 1. We also confirm that at |k| ρ<inf>e</inf> > ~ 2, the energy density of B and E approaches equipartition, suggesting that energy transfer is near complete.
AU - Ergun,RE
AU - Vo,T
AU - Qi,Y
AU - Chasapis,A
AU - Pathak,N
AU - Usanova,ME
AU - Ahmadi,N
AU - George,H
AU - Schwartz,SJ
DO - 1538-4357/ae53d8
PY - 2026///
SN - 0004-637X
TI - Evidence of a Subkinetic Spectral Break in a Strongly Turbulent Collisionless Plasma
T2 - Astrophysical Journal
UR - http://dx.doi.org/10.3847/1538-4357/ae53d8
VL - 1001
ER -