In situ Measurement of Curvature of Magnetic Field in Turbulent Space Plasmas: A Statistical Study

TL;DR

This study analyzes magnetic field curvature in turbulent space plasmas using MMS data, revealing its intermittent distribution and potential impact on particle energization processes.

Contribution

It provides the first statistical characterization of magnetic curvature in space plasmas based on in situ measurements, linking curvature distribution to turbulence.

Findings

Curvature PDF exhibits power-law tails at high and low values.

High curvature regions are near weak magnetic fields.

Low curvature correlates with small normal force on field lines.

Abstract

Using in situ data, accumulated in the turbulent magnetosheath by the Magnetospheric Multiscale (MMS) Mission, we report a statistical study of magnetic field curvature and discuss its role in the turbulent space plasmas. Consistent with previous simulation results, the Probability Distribution Function (PDF) of the curvature is shown to have distinct power-law tails for both high and low value limits. We find that the magnetic-field-line curvature is intermittently distributed in space. High curvature values reside near weak magnetic-field regions, while low curvature values are correlated with small magnitude of the force acting normal to the field lines. A simple statistical treatment provides an explanation for the observed curvature distribution. This novel statistical characterization of magnetic curvature in space plasma provides a starting point for assessing, in a turbulence context, the applicability and impact of particle energization processes, such as curvature drift, that rely on this fundamental quantity.