Effect of electron ambient plasmas in reconnection jets and dipolarization fronts : MMS initial results
Abstract:With the successful launch of Magnetospheric Multiscale Misssion (MMS), it becomes possible to observe the dynamic signatures of magnetospheric transients with high-time resolution measurements of electromagnetic fields and plasma. The Active Spacecraft Potential Control (ASPOC) neutralizes the spacecraft potential by releasing positive charge produced by indium and thereby controlling the spacecraft potential in order to enable accurate measurements also in sparse plasma environments essential to study properties of reconnection. Since the current balance around the spacecraft is maintained by contribution also from the ambient plasma, predominantly electrons, ASPOC beam current values combined with spacecraft potential data from FIELDS instruments enable to deduce the ambient electron plasma parameters . Particularly, using data from multi-spacecraft measurements with different ASPOC current levels and FIELDS data, parameters on ambient electron temperature and density can be deduced.
Monitoring the environmental plasma parameters are essential to determine the accurate scales of the structure or wave length relative to plasma scales and hence to understand the physical processes. In this study we investigate the changes of the electron parameters in the transient structures such as the magnetic field disturbance forming at the front of BBF/flow bursts, called dipolarization front (DF), and reconnection jets in thin current sheets obtained by MMS mainly during the commissioning phase when the spacecraft traversed the near-Earth tail.