Lai S. T., M. Martinez-Sanchez, K. Cahoy, M. F. Thomsen, Y. Shprits, W. Lohmeyer, F. K. Wong, (2017), Does Spacecraft Potential Depend on the Ambient Electron Density?, Ieee Transactions On Plasma Science, 45, 2875-2884, doi:10.1109/TPS.2017.2751002

## Abstract

In this paper, we address the question of whether spacecraft potential depends on the ambient electron density. In Maxwellian space plasmas, the onset of spacecraft charging does not depend on the ambient electron density. The balance of electron currents causes the incoming electrons to balance with the outgoing secondary electrons. The onset is controlled by the critical or anticritical temperature of the ambient electrons, but not the electron density. Above the critical temperature, charging to negative potential occurs. If the energy of the incoming electrons increases to well beyond the second crossing point of the secondary electron yield (SEY), the value of SEY decreases to well below unity. When the secondary electron current is negligible compared with the primary electron current, the spacecraft potential is governed solely by the balance of the incoming electrons and the sum of the currents of the repelled electrons and the attracted ions. In neutral space plasma, the electron and ion charges cancel each other. But if the space plasma deviates from being neutral, then the densities can have effect on the spacecraft potential. If the ambient plasma deviates significantly from equilibrium, a non-Maxwellian electron distribution may result. For a kappa distribution, one can show that the spacecraft charging level is independent of the ambient electron density. For a double Maxwellian distribution, the spacecraft charging level depends on the electron densities. For a conducting spacecraft charging in sunlight, the charging level is low and positive. It also depends on the ambient electron density. For a dielectric spacecraft in sunlight, the high-level negative-voltage charging on the shadowed side may extend to the sunlit side and block the photoelectrons trying to escape from the sunlit side. In this case, the charging level does not depend on ambient electron density. Using coordinated environmental and spacecraft charging data obtained from the Los Alamos National Laboratory geosynchronous satellites, we showed some results confirming that spacecraft potential is indeed often independent of the ambient electron density.## Authors (sorted by name)

Cahoy Lai Lohmeyer Martinez-Sanchez Shprits Thomsen Wong## Journal / Conference

Ieee Transactions On Plasma Science## Bibtex

@ARTICLE{10.1109/TPS.2017.2751002,
author={S. T. Lai and M. Martinez-Sanchez and K. Cahoy and M. F. Thomsen and Y. Shprits and W. Lohmeyer and F. K. Wong},
journal={IEEE Transactions on Plasma Science},
title={Does Spacecraft Potential Depend on the Ambient Electron Density?},
year={2017},
volume={45},
number={10},
pages={2875-2884},
abstract={In this paper, we address the question of whether spacecraft potential depends on the ambient electron density. In Maxwellian space plasmas, the onset of spacecraft charging does not depend on the ambient electron density. The balance of electron currents causes the incoming electrons to balance with the outgoing secondary electrons. The onset is controlled by the critical or anticritical temperature of the ambient electrons, but not the electron density. Above the critical temperature, charging to negative potential occurs. If the energy of the incoming electrons increases to well beyond the second crossing point of the secondary electron yield (SEY), the value of SEY decreases to well below unity. When the secondary electron current is negligible compared with the primary electron current, the spacecraft potential is governed solely by the balance of the incoming electrons and the sum of the currents of the repelled electrons and the attracted ions. In neutral space plasma, the electron and ion charges cancel each other. But if the space plasma deviates from being neutral, then the densities can have effect on the spacecraft potential. If the ambient plasma deviates significantly from equilibrium, a non-Maxwellian electron distribution may result. For a kappa distribution, one can show that the spacecraft charging level is independent of the ambient electron density. For a double Maxwellian distribution, the spacecraft charging level depends on the electron densities. For a conducting spacecraft charging in sunlight, the charging level is low and positive. It also depends on the ambient electron density. For a dielectric spacecraft in sunlight, the high-level negative-voltage charging on the shadowed side may extend to the sunlit side and block the photoelectrons trying to escape from the sunlit side. In this case, the charging level does not depend on ambient electron density. Using coordinated environmental and spacecraft charging data obtained from the Los Alamos National Laboratory geosynchronous satellites, we showed some results confirming that spacecraft potential is indeed often independent of the ambient electron density.},
keywords={astrophysical plasma;electron density;plasma density;plasma temperature;secondary electron emission;space vehicles;spacecraft charging;sunlight;surface charging;ion charges;spacecraft potential;nonMaxwellian electron distribution;spacecraft charging level;ambient electron density;incoming electrons;secondary electron current;primary electron current;secondary electron yield;Los Alamos National Laboratory geosynchronous satellites;high-level negative-voltage charging;Space vehicles;Plasma temperature;Ions;Electric potential;Satellites;Distribution functions;Charging in sunlight;critical temperature;electron density;geosynchronous satellites;ion density;Maxwellian distribution;plasma probes;space plasmas;spacecraft charging;spacecraft potential},
doi={10.1109/TPS.2017.2751002},
ISSN={0093-3813},
month={Oct},}