Event Details

Plasma Turbulence in Earth’s Magnetosphere: New Insights from the Magnetospheric Multiscale Mission

Abstract:

Turbulence, the highly nonlinear behavior of fluids, plays a fundamental role in particle energisation in plasmas by transferring the energy contained in large-scale fluctuations to small length scales, where it can be more easily dissipated. However, in the collisionless plasmas that are often encountered in space, disentangling the multitude of processes through which energy is transferred from the turbulent fluctuations into the particles is a major open area of research. Over the past several years, high-resolution, multi-spacecraft measurements from NASA’s Magnetospheric Multiscale (MMS) mission have allowed the examination of turbulence within the Earth’s magnetosphere in greater detail than previously possible, providing new insight into the small-scale dynamics that lead to turbulent dissipation in collisionless plasmas. In this presentation, we give a brief overview of the various turbulent regions encountered in Earth magnetosphere, including the magnetosheath, Kelvin-Helmholtz vortices on the magnetopause, and the plasma sheet, and discuss the impact turbulence can have within these environments. We then highlight several new results on the small-scale dynamics of turbulent plasmas, which required the high-quality measurements from MMS. Using MMS observations from the magnetosheath, we examine the origin of the turbulent electric fields, which play a key role in energy dissipation and provide insight into the small-scale nonlinear dynamics, through the direct measurement of generalized Ohm’s law. Furthermore, we examine the role turbulence plays in driving the newly discovered “electron-only” magnetic reconnection, which may impact how turbulent energy dissipation is partitioned between different particles species under different turbulence conditions.