All pages tagged MMS

With the launch of the MMS spacecraft a few years ago, we now have the capability to study turbulence in the magnetosheath at higher resolution than ever before. Here, I will present recent work using the MMS data to investigate the nature of kinetic turbulence at electron scales and the nature of the damping mechanisms of the turbulence at these scales. Focussing on an interval of magnetosheath data near the magnetopause, the nature of the turbulence was found to change as the electron inertial scale is reached, transitioning to a regime of inertial kinetic Alfven turbulence - I will present observations and a theoretical model for this turbulence. I will also describe our recent application of a field-particle correlation technique to the MMS data, which enables the energy transfer in velocity space to be determined. The results of this are consistent with the presence of electron Landau damping in the kinetic range.

Etienne Behar, Fouad Sahraoui

Laboratoire de Physique des Plasmas, CNRS - École polytechnique - Sorbonne Université - Observatoire de Paris, Université Paris-Sud, Université Paris-Saclay, F-91128 Palaiseau, France

We present our current work on the analysis of MMS data carried out in particular with particle velocity distribution functions (VDF). We propose methods that tackle the high time resolution of these four-dimensional data sets, in various reference frames and coordinate systems. In particular, we explore the feasibility of obtaining spatial and time derivatives of the VDF, with the inherent price in terms of time resolution/integration. Together with field measurements, these derivatives enable the quantification of the various terms of the Poisson-Vlasov equations, with the ultimate goal of a direct measurement of the energy exchange taking place between fields and particles, as a function of velocity, following the effort initiated by Howes et al. 2017 and Chen et al. 2019.