Charging of nanograins in cold dusty plasmas: from noctulescent clouds to Enceladus plume and cometary environments (Invited)
Abstract
In cold plasmas, nanograins can be smaller than the Landau scale: the distance at which the interaction energy of two electrons equals their thermal energy. In that case the collected fluxes of ambient plasma particles are increased by the induced grains' polarization, which reduces the charging time scales. Furthermore the grains' electric charge is discretized and has a most probable equilibrium value close to one electron charge, roughly independent of the nanograins' size in a wide range of sizes. Such conditions hold in various environments, as the Earth's mesosphere - producing noctulescent clouds and Polar Mesospheric Summer Echoes, near comets, in planetary environments of the outer solar system - for example in the plume of Saturn's moon Enceladus, and in the interstellar medium. We derive analytical formulas for the electric charge of nanograins in cold dense dusty plasmas, which take into account changes in plasma particles' concentrations due to dust charging. We show in particular that the charge-to-mass ratio of nanograins does increase faster with decreasing size than in the case of larger grains; this affects the nanodust dynamics and pick-up process. We also derive consequences on the minimum grain size and discuss some applications in several solar system environments.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.P32B..03M
- Keywords:
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- 7849 SPACE PLASMA PHYSICS Plasma interactions with dust and aerosols;
- 6282 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS Enceladus;
- 5759 PLANETARY SCIENCES: FLUID PLANETS Rings and dust;
- 6015 PLANETARY SCIENCES: COMETS AND SMALL BODIES Dust