Abstract
The backflow plume from an electric thruster can lead to the
accumulation of electrostatic charge on the spacecraft, leading to a
negative charge. Interactions between the plume and solar wind can
further influence the charge distribution, resulting in variations in
spacecraft potential and interference with sensitive instruments. A 3D
Particle-In-Cell (PIC) simulation tool within the Spacecraft Plasma
Interaction Software (SPIS) is used to compute spacecraft charging
effects from 0.067 to 1 Astronomical unit (AU). The study examines the
dynamic behaviour of ambient electrons and ions, thruster electrons, and
CEX-ions, as well as photoemission and secondary electrons, and solar
photon flux impact on the spacecraft potential. The main finding is the
demonstration that the high dominance of CEX-ions and thruster electrons
helps to achieve a low and stable negative potential ranging from -2 to
-6 V from 0.067 AU to 1 AU when the thruster is on, as opposed to the
varying range of -5 to +9 V with the thruster off. Other findings are
that the elimination of photoelectrons or secondary electrons has a
comparatively greater impact on spacecraft potential when the thruster
is off, as opposed to when the thruster is on. Both CEX-ions and
thruster electrons significantly contribute to the mitigation and
regulation of spacecraft potential towards a less negative potential in
situations where photoemission or secondary electrons are absent or
relatively unimportant.