Subion Scale Turbulence Driven by Magnetic Reconnection

TL;DR

This paper provides observational evidence that magnetic reconnection directly drives subion scale turbulence in magnetospheric plasmas by transferring energy to smaller scales, supported by simulations and a novel measurement approach.

Contribution

It introduces a spatial coarse-grained Hall MHD model to measure energy transfer rates, demonstrating reconnection's role in generating small-scale turbulence in space plasmas.

Findings

Magnetic reconnection transfers energy to subion scales in magnetospheric plasmas.

The coarse-grained model effectively measures nonlinear energy transfer across scales.

Simulation results support observational evidence of reconnection-driven turbulence.

Abstract

The interplay between plasma turbulence and magnetic reconnection remains an unsettled question in astrophysical and laboratory plasmas. Here we report the first observational evidence that magnetic reconnection drives subion scale turbulence in magnetospheric plasmas by transferring energy to small scales. We employ a spatial coarse-grained model of Hall magnetohydrodynamics, enabling us to measure the nonlinear energy transfer rate across scale $\ell$ at position $x$. Its application to Magnetospheric Multiscale mission data shows that magnetic reconnection drives intense energy transfer to subion scales. This observational evidence is remarkably supported by the results from Hybrid Vlasov-Maxwell simulations of turbulence to which the coarse-grained model is also applied. These results can potentially answer some open questions on plasma turbulence in planetary environments.