ar X iv : a st ro - p h / 02 05 50 9 v 1 2 9 M ay 2 00 2 1 Charging Processes for Dust Particles in Saturn ’ s Magnetosphere

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 The charging time for one 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. The dynamics of dust, submillimeter-sized dust grains, is a fascinating area of study of our solar system's dynamical evolution. Small particles, especially charged particles, respond to other forces than gravitational, in particular, electromagnetic forces. The dust particle's properties and dynamics fall into a complex regime between nuclear physics and electromagnetic physics and gravitational physics. In order to calculate charges on a dust particle around a planet, we must characterize: 2 • The planet's magnetospheric features: its magnetic field and plasma, • The physical processes onto the dust particle that generate currents, and • The material properties of the dust particle. In this paper, we make reference to results of charging of dust particles in Earth's magnetosphere ([2],[3]). Earth is an interesting charging environment for dust particles , in part, because the dynamic magnetospheric plasma shows steep changes in the electron and ion energies and densities, therefore, the electron energy can be quite high (e.g. a few thousand eV). Table 1 lists some basic parameters comparing Saturn's and Earth's magnetosphere.