Charging processes for dust particles in Saturn's magnetosphere

Abstract

We investigated the electrostatic charging behavior of submillimeter-sized dust particles located in Saturn's magnetosphere. The charging effects we considered included electron/ion capture from the magnetospheric plasma, electron/ion capture from the solar-wind plasma, the photoelectric effect from solar radiation, and secondary electron emission from energetic electrons. In our results, we show charging times and equilibrium potentials for particles located in different regions of Saturn's magnetosphere. We find that charging in Saturn's magnetosphere is not particularly sensitive to the dust particle's material properties. The equipotential ranges from $\sim$-2 V at 3.5 R$_S$, decreasing to $\sim$-5 V at 6 R$_S$, and then increasing to $\sim$-1.5 V at 10 R$_S$. The charging time for micron-sized particles is a few minutes, and for 0.01 micron-sized particles the charging time is 6 hours (or more). The latter is a significant fraction of Saturn's rotation period.