Case Study of Suprathermal Electrons in the Martian Wake

The Martian magnetotail is home to plasma processes such as reconfiguration of the magnetic environment through reconnection, charged particle transport and acceleration, and precipitation onto the atmosphere. Mars magnetotail potential is highly variable given the influence of remanent crustal magnetism on an otherwise induced magnetic field. Plasma acceleration and transport can provide insight towards the workings of Mars hybrid magnetic field. We present a case study of electron acceleration in the Martian magnetotail region using data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) Solar Wind Electron Analyzer (SWEA) and Magnetometer instruments. Mapping suprathermal electron distribution functions in the magnetotail provides information about the nature and distribution of accelerated electron source regions. Electron energy-pitch angle distributions describe the sampled plasma source regions and configuration of the observed planetary magnetic field. This provides insight into Mars varied potential structure as well as the magnetic field topology influencing the observed suprathermal electrons. We present MAVEN electron and magnetic field data obtained past the dusk terminator in the magnetotail and downstream of strong crustal magnetic fields. As the spacecraft descended from 1.5 RM to 1 RM, above the surface, open magnetic field topology is deduced from the presence of a loss cone in the electron pitch angle distributions. Electron energy distributions in this region show no evidence for acceleration. At ~1 RM, trapped electrons are observed, implying closed magnetic field topology. The spacecraft crossed one or more current sheets, as revealed by large (<180 deg) magnetic field rotations. At the same time, accelerated electrons were observed, with flat-top distributions extending to ~100 eV. Below 1RM, counter-streaming electrons (field aligned in both directions) indicated draped magnetic field topology. These analyses will allow us to produce an algorithm in the future to statistically characterize the features and source regions of suprathermal electrons in the magnetotail.