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Investigation of the current collected by a positively biased satellite with application to electrodynamic tethers
Author(s) -
Janeski John A.,
Scales Wayne A.,
Hall Christopher D.
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019473
Subject(s) - physics , satellite , current (fluid) , plasma , electron , bow shock (aerodynamics) , magnetic field , computational physics , ionosphere , field (mathematics) , astrophysical plasma , geophysics , mechanics , shock wave , astronomy , nuclear physics , quantum mechanics , thermodynamics , mathematics , pure mathematics
The interaction between a positively biased body traveling through an ionospheric space plasma has direct application to electrodynamic tether (EDT) systems. A 2‐D3 v particle‐in‐cell model has been developed to study the plasma dynamics near a positively charged EDT system end‐body and their impact on the current collected. The results show that the azimuthal current structures observed during the reflight of the tethered satellite system (TSS‐1R) mission develop in the simulations and are found to enhance the current collected by the satellite by 67% when the magnetic field is ∼15° off of perpendicular to the orbital velocity. As the component of the magnetic field in the simulation's plane increases, the electrons are not able to easily cross the field lines causing plasma lobes to form in the + y and − y regions around the satellite. The lobes limit the current arriving at the satellite and also cause an enhanced wake to develop. A high satellite bias causes a stable bow shock structure to form in the ram region of the satellite, which limits the number of electrons entering the sheath region and thus limits the current collected. Electron‐neutral collisions are found to destabilize the bow shock structure, and its current limiting effects were negated. Analytical curve fits based on the simulations are presented in order to characterize the dependence of the current collected on the magnetic field's orientation, space plasma magnetization, and satellite potential. The variations in the collected current induced by space plasma environmental changes may introduce new instabilities in an EDT system's dynamics.