Premium
Collisionless Electron Dynamics in the Magnetosheath of Mars
Author(s) -
Schwartz S. J.,
Andersson L.,
Xu S.,
Mitchell D. L.,
Akbari H.,
Ergun R. E.,
Mazelle C.,
Thaller S. A.,
Sales A. R. N.,
Horaites K.,
DiBraccio G. A.,
Meziane K.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl085037
Subject(s) - magnetosheath , bow shock (aerodynamics) , physics , electron , mars exploration program , solar wind , population , computational physics , ionization , exosphere , kinetic energy , bow wave , shock wave , atomic physics , magnetopause , plasma , mechanics , astrobiology , classical mechanics , quantum mechanics , ion , demography , sociology
Electron velocity distributions in Mars's magnetosheath show a systematic erosion of the energy spectrum with distance downstream from the bow shock. Previous attempts to model this erosion invoked assumptions to promote electron ionization impact collisions with Mars's neutral hydrogen exosphere. We show that the near collision‐free magnetosheath requires a kinetic description; the population of electrons at any location is a convolution of electrons arriving from more distant regions that ultimately map directly to the solar wind. We construct a simple model that captures all the essential physics. The model demonstrates how the erosion of the electron distributions is the result of the trapping, escape, and replacement of electrons that traverse the global bow shock; some are temporarily confined to the expanding cavity formed by the cross‐shock electrostatic potential. The model also has implications for the ability of solar wind electrons to reach altitudes below the pileup boundary.