Earth Magnetic Field Effects on Particle Sensors on LEO Satellites

Kinetic simulation results are presented for the interaction of spacecraft with space environment in low Earth orbit. Case studies are considered for DEMETER, for which small but distinctive potential variations have been measured on Instrument Champ Electrique (ICE) sensors, as the satellite goes through regions where the magnetic field B^→ is nearly parallel to the satellite velocity v^→. Our results point to a small variation in the potential of ICE probes under these conditions, but owing to the smallness of the signal and inherent statistical noise in our simulations, it is not possible to unambiguously explain observations. An earlier study of magnetic field effects on the Swarm electric field instrument is extended by computing Langmuir probe characteristics with and without a magnetic field. The possibility of probe crosstalk is also examined by comparing collected currents when the two probes have same and opposite bias voltages. Accounting for a representative ionospheric magnetic field is found to lead to appreciable quantitative differences in the probe characteristics. No significant crosstalk or mutual coupling is predicted between the probes under normal operation.