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A collisional test particle model of electrons at a comet
File | Description | Size | Format | |
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stac055.pdf | Published version | 2.41 MB | Adobe PDF | View/Open |
Title: | A collisional test particle model of electrons at a comet |
Authors: | Stephenson, P Galand, M Deca, J Henri, P Carnielli, G |
Item Type: | Journal Article |
Abstract: | We have developed the first 3D collisional model of electrons at a comet, which we use to examine the impact of electron-neutral collisions in the weakly outgassing regime. The test-particle Monte Carlo model uses electric and magnetic fields from a fully kinetic Particle-in-Cell (PiC) model as an input. In our model, electrons originate from the solar wind or from ionization of the neutral coma, either by electron impact or absorption of an extreme ultraviolet photon. All relevant electron-neutral collision processes are included in the model including elastic scattering, excitation, and ionization. Trajectories of electrons are validated against analytically known drifts and the stochastic energy degradation used in the model is compared to the continuous slowing down approximation. Macroscopic properties of the solar wind and cometary electron populations, such as density and temperature, are validated with simple known cases and via comparison with the collisionless PiC model. We demonstrate that electrons are trapped close to the nucleus by the ambipolar electric field, causing an increase in the efficiency of electron-neutral collisions. Even at a low-outgassing rate (Q = 1026 s−1), electron-neutral collisions are shown to cause significant cooling in the coma. The model also provides a multistep numerical framework that is used to assess the influence of the electron-to-ion mass ratio, enabling access to electron dynamics with a physical electron mass. |
Issue Date: | 1-Apr-2022 |
Date of Acceptance: | 14-Dec-2021 |
URI: | http://hdl.handle.net/10044/1/94174 |
DOI: | 10.1093/mnras/stac055 |
ISSN: | 0035-8711 |
Publisher: | Royal Astronomical Society |
Start Page: | 4090 |
End Page: | 4108 |
Journal / Book Title: | Monthly Notices of the Royal Astronomical Society |
Volume: | 511 |
Issue: | 3 |
Copyright Statement: | © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited |
Keywords: | Science & Technology Physical Sciences Astronomy & Astrophysics comets: general comets: individual: 67P/CG SUPRATHERMAL ELECTRONS ENERGY DEPOSITION PLASMA ROSETTA RPC WATER 67P/CHURYUMOV-GERASIMENKO PRECIPITATION IONOSPHERE EXCITATION Astronomy & Astrophysics 0201 Astronomical and Space Sciences |
Publication Status: | Published |
Online Publication Date: | 2022-02-07 |
Appears in Collections: | Space and Atmospheric Physics Physics Faculty of Natural Sciences |
This item is licensed under a Creative Commons License