Currents Within the Bursty Bulk Flow Braking Region as Observed by the Magnetospheric Multiscale Mission
Résumé
Bursty Bulk Flows (BBFs), thought to be ejecta from reconnection in the near-Earth magnetotail, are an important means of mass, energy, and magnetic flux transport in the magnetosphere. Understanding how this energy is redirected within the braking region, where the flow impinges on the dipolar field near Earth, is an important question. In this study, properties of the small-scale currents in the BBF braking region are examined with particular emphasis on the nature of the field-aligned component of the currents. Previous studies have suggested that the instability of field-aligned currents associated with turbulence may generate double layers and electron phase space holes observed in the region, thereby providing a collisionless dissipation mechanism for the turbulence. However, direct information about these small-scale currents was inaccessible with the previous data sets. A campaign of burst data collection including Fast Plasma Investigation data from the magnetotail focused on BBF events during August of 2016 has made the present study possible. The work provides insights into the process of energy dissipation by turbulence in the BBF braking region.