Journal article
Ion trapping by dust grains: Simulation applications to the Enceladus plume: Enceladus Plume Ions
Journal of geophysical research. Planets, Vol.122(4), pp.729-743
04/2017
DOI: 10.1002/2016JE005235
Abstract
Using a particle-in-cell electrostatic simulation, we examine the conditions that allow low-energy ions, like those produced in the Enceladus plume, to be attracted and trapped within the sheaths of negatively charged dust grains. The conventional wisdom is that all new ions produced in the Enceladus plume are free to get picked up (i.e., accelerated by the local E field to then undergo vB acceleration). However, we suggest herein that the presence of submicron-charged dust in the plume impedes this pickup process since the local grain electric field greatly exceeds the corotation E fields. The simulations demonstrate that cold ions will tend to accelerate toward the negatively charged grains and become part of the ion plasma sheath. These trapped ions will move with the grains, exiting the plume region at the dust speed. We suggest that Cassini's Langmuir probe is measuring the entire ion population (free and trapped ions), while the Cassini magnetometer detects the magnetic perturbations associated with pickup currents from the smaller population of free ions, with this distinction possibly reconciling the ongoing debate in the literature on the ion density in the plume.
Details
- Title: Subtitle
- Ion trapping by dust grains: Simulation applications to the Enceladus plume: Enceladus Plume Ions
- Creators
- W. M. Farrell - Goddard Space Flight CenterJ.-E. Wahlund - Swedish Institute of Space PhysicsM. Morooka - Swedish Institute of Space PhysicsW. S. Kurth - University of IowaD. A. Gurnett - University of IowaR. J. MacDowall - Goddard Space Flight Center
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Planets, Vol.122(4), pp.729-743
- DOI
- 10.1002/2016JE005235
- ISSN
- 2169-9097
- eISSN
- 2169-9100
- Grant note
- name: NASA Cassini
- Language
- English
- Date published
- 04/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455273602771
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