Imperial College London
Alternate

ProfessorMarinaGaland

Faculty of Natural Sciences, Department of Physics

Professor in Planetary Science
 
 
 
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Contact

 

m.galand Website

 
 
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Location

 

Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Stephenson:2022:mnras/stac055,
author = {Stephenson, P and Galand, M and Deca, J and Henri, P and Carnielli, G},
doi = {mnras/stac055},
journal = {Monthly Notices of the Royal Astronomical Society},
pages = {4090--4108},
title = {A collisional test particle model of electrons at a comet},
url = {http://dx.doi.org/10.1093/mnras/stac055},
volume = {511},
year = {2022}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - 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.
AU  - Stephenson,P
AU  - Galand,M
AU  - Deca,J
AU  - Henri,P
AU  - Carnielli,G
DO  - mnras/stac055
EP  - 4108
PY  - 2022///
SN  - 0035-8711
SP  - 4090
TI  - A collisional test particle model of electrons at a comet
T2  - Monthly Notices of the Royal Astronomical Society
UR  - http://dx.doi.org/10.1093/mnras/stac055
UR  - http://hdl.handle.net/10044/1/94174
VL  - 511
ER  -
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