2020/10/10 by Luca Franci, Franci, Luca, D. Del Sarto +15 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Plasma Physics (physics.plasm-ph) #Solar and Space Plasma Dynamics #Space Physics (physics.space-ph)
paper · pdf · doi:10.48550/arxiv.2010.05048
openalex publication_date 2020/10/10 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
How the turbulent energy cascade develops below the magnetohydrodynamic scales in space and astrophysical plasmas is a major open question. Here, we measure the power spectrum of magnetic fluctuations in Parker Solar Probe's observations close to the Sun and in state-of-the-art numerical simulations of plasma turbulence. Both reveal a power-law behavior with a slope compatible with -11/3 at scales smaller than the ion characteristic scales, steeper than what is typically observed in the solar wind and in the Earth's magnetosheath. We explain such behavior by developing a simple two-fluid model which does not require any kinetic processes nor electron-inertia effects. This is characterized by a significant contribution of the ion kinetic energy to the total turbulent energy cascade at sub-ion scales, although the dynamics is driven by the magnetic field through the current density. We expect that this regime may be relevant for a broad class of low-beta plasmas, e.g. the solar corona, non-relativistic magnetized jets and disks, and laboratory plasmas.