Addressing the effects of background plasma and wake formation on nanosatellites with electric propulsion using a 3D Particle In Cell code

Abstract

3D-PIC (Particle In Cell) simulations were performed to emulate the dynamics and collection of plasma particles onto the surface of the UWE-IV, a satellite of miniaturized dimensions (CubeSat) launched in 2018. We review the electrostatic potential, currents collected and plasma disturbances of the CubeSat and characterize them by numerical simulation over Low Earth Orbits (LEO), in two general cases: as a passive satellite and with active thrusters without regard of neutralization units. During one orbital period the passive CubeSat drives an isotropic impingement of plasma electrons, that (because their higher mobility regarding ions) govern a negative surface potential. However, by the time-evolution of the charge sheath, we relate that potential barriers may be forming around the satellite that can reduce the collection of electrons over spacecraft surfaces. When thrusters are fired, spacecraft becomes more negatively charged than for a passive satellite, and their potential energy E sc is about hundreds of times larger than the ambient ion flowing energies, E i . In this case, ion density maps of ambient oxygen ( O + ), show particles fill in the ion void (wake) zone due to bare electrostatic attraction by a (growing) negative satellite potential. The experiment was repeated in different orbit altitudes with varying plasma densities, showing that in space zones with greater concentration of plasma ions, the satellite potential is less negative, ultimately linked to this near-wake ion-focusing collection. Thus, we conclude that if thrusters operate in LEO altitudes, where the relatively higher plasma concentrations are (equatorial orbits of 300–500 km), large negative potentials can be avoided due to the natural rule of ambient ion dynamics. This study can be important for operations of future miniaturized satellites using this type of thruster technologies.