Turbulence-generated proton-scale structures in the terrestrial magnetosheath

TL;DR

This study combines numerical simulations and multi-point observations to demonstrate that turbulence in the Earth's magnetosheath generates proton-scale current sheets, which are linked to magnetic field discontinuities and plasma heating.

Contribution

First experimental evidence showing that turbulence-generated current sheets in the magnetosheath occupy the tails of magnetic field derivative distributions.

Findings

Strong current sheets are associated with extremal magnetic field derivatives.

Approximately a hundred proton-scale current sheets observed in one hour.

Turbulence contributes to non-homogeneous plasma heating.

Abstract

Recent results of numerical magnetohydrodynamic simulations suggest that in collisionless space plasmas turbulence can spontaneously generate thin current sheets. These coherent structures can partially explain intermittency and the non-homogenous distribution of localized plasma heating in turbulence. In this Letter Cluster multi-point observations are used to investigate the distribution of magnetic field discontinuities and the associated small-scale current sheets in the terrestrial magnetosheath downstream of a quasi-parallel bow shock. It is shown experimentally, for the first time, that the strongest turbulence generated current sheets occupy the long tails of probability distribution functions (PDFs) associated with extremal values of magnetic field partial derivatives. During the analyzed one hour long time interval, about a hundred strong discontinuities, possibly proton-scale current sheets were observed.