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Langmuir probe, Suprathermal Ion Imager, Ionospheric perturbations

Imtiaz, Nadia

Supervisor and department: Richard Marchand Physics

Examining committee member and department: Richard Marchand Physics Andrei Smolyakov Physics, Saskatchewan Carsten Krauss Physics Kim Chow Physics Frances Fenrich Physics

Department: Department of Physics

Specialization:

Date accepted: 2013-11-14T14:13:39Z

Graduation date: 2014-06

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: This PhD thesis presents numerical studies of the ionosphere dynamics and of the interaction between ionospheric plasma and spacecraft instruments.The main results of my research are the following:A first study presents a simple model to account for magnetic field perturbations in response to geophysical phenomena such as earthquakes.Following an earthquake, large neutral density and velocity perturbations reach altitudes of $ 150-350 $ km, where significant coupling between the neutral atmosphere and the ionosphere occurs.Photoionization and collisional friction between plasma and the neutral exosphere then results in a rapid variation in ionospheric plasma parameters.This in turn leads to the generation of two types of waves: shear Alfv-en and the compressional modes.Variations in the total electron content TEC are also computed for the ion acoustic mode and the compressional mode by considering density perturbations along and transverse to the magnetic field.The second part of my work considers the interaction between ionospheric plasma and spacecraft instruments under different plasma conditions.This is achieved by simulating space plasma interaction with two different particle sensors; namely, DEMETER-s Segmented Langmuir probe SLP and JOULEII Suprathermal Ion imager SII.The current characteristics of the SLP are computed with particle in cell PIC code, under different plasma conditions.The current collected by each segment varies with the orientation of the plasma flow velocity, the plasma composition and with the orientation of the magnetic field.For validation of the simulations, the computed characteristics are compared with DEMETER in situ measurements.Simulation results are found to be in good agreement with measurements.Finally, the impact of plasma flow on ion velocity distributions in the vicinity of the SII sensor aperture is numerically investigated.It is observed that the plasma flow modifies the electrostatic sheath and affects the velocity distributions of $NO^+$ and $O 2^+$ ions at the aperture of the SII sensor. The velocity distribution functions at the SII aperture are used to compute ion fluxes on the SII micro channel plate MCP and computed fluxes are compared with JOULEII measurements.

Language: English

DOI: doi:10.7939-R3FB4WV38

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Imtiaz, Nadia

Fuente: https://era.library.ualberta.ca/


Introducción



University of Alberta Numerical study of ionospheric response to perturbations and interaction with spacecraft instruments by Nadia Imtiaz A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Physics c Nadia Imtiaz Spring 2014 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only.
Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the authors prior written permission. “To my Daughter, Daniya” Abstract This PhD thesis presents numerical studies of the ionosphere dynamics and of the interaction between ionospheric plasma and spacecraft instruments.
The main results of my research are the following: A first study presents a simple model to account for magnetic field perturbations in response to geophysical phenomena such as earthquakes.
Following an earthquake, large neutral density and velocity perturbations reach altitudes of 150 − 350 km, where significant coupling between the neutral atmosphere and the ionosphere occurs.
Photoionization and collisional friction between plasma and the neutral exosphere then results in a rapid variation in ionospheric plasma parameters.
This in turn leads to the generation of two types of waves: shear Alfvén and the compressional modes.
Variations in the total electron content (TEC) are also computed for the ion acoustic mode and the compressional mode by c...





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