Physical Processes in the Dusty Plasma of the Enceladus Plume

Abstract

This chapter presents a short overview of physical processes in a specific plasma region (a so-called plume) found by the Cassini orbiter in the vicinity of the icy moon Enceladus. In particular, we summarize highlights of scientific results which have been performed by German research groups in GFZ German Research Centre for Geosciences, Potsdam and Technical University of Braunschweig as part of the Special Priority Program “PlanetMag” of the Deutsche Forschungsgemeinschaft between 2013 and 2016. The highlights cover mostly those theoretical and numerical studies in which measurements of different Cassini instruments could be compared with theory or where the phenomenon has a diagnostic application. Dust charging, role of dust size distributions, and dust charge fluctuations are discussed. The findings are used for interpretations of the Cassini Plasma Spectrometer data and improve constraints on the dust characteristics. Then the main forces and dust dynamics are discussed in conditions relevant for the near-Enceladus environment. It is also examined how the charged dust can affect the plasma shielding length which is of importance for the reliable Cassini Langmuir probe measurements. Considering the dust grains as heavy negative ion species, the electric conductivity tensor is modified, whose elements are the key quantities for understanding the magnetic field perturbations registered by the Cassini Magnetometer during Enceladus flybys.