Electron Wing-Like Structures Formed at a Negatively Charged SpacecraftMoving in a Magnetized Plasma

摘要

Spacecraft-plasma interactions are studied with self-consistent numerical simulations of magnetized plasmas, where electrons are strongly magnetized whereas ions are weakly magnetized. It is found that for a spacecraft in such a magnetized plasma corresponding to a low Earth orbit, electrons can be reflected from a negatively charged spacecraft and then guided by geomagnetic field lines. The reflected electrons can leave a sharp trail like wings if the spacecraft size is greater than an average electron gyroradius of the environment. Such an electron wing-like structure is associated with propagating Langmuir waves. This results in nontrivial asymmetric electrostatic potentials close to the spacecraft and even farther than the Debye screening distance. The convective electric field also gives rise to a differential potential of the spacecraft with respect to the plasma, resulting in yet another asymmetry in the plasma dynamics and the potential distribution around the spacecraft. These asymmetries in the plasma dynamics can significantly influence in-situ measurements of space plasma. The results show a good qualitative agreement with actual measurements by a satellite in the polar regions.