Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT
This work presents a study of the electron plasma lines observed by the incoherent scatter radar EISCAT. The work is focusing on two parts. On one hand, the design of a plasma line experiment for the EISCAT system with an improved spatial resolution. On the other hand, the comparison of the plasma l...
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ftdatacite:10.5281/zenodo.51817 2023-05-15T16:04:29+02:00 Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT Guio, Patrick 1998 https://dx.doi.org/10.5281/zenodo.51817 https://zenodo.org/record/51817 unknown Zenodo http://munin.uit.no/handle/10037/2976 https://tel.archives-ouvertes.fr/tel-00481443v1 http://cat.inist.fr/?aModele=afficheN&cpsidt=194412 http://munin.uit.no/handle/10037/2976 https://tel.archives-ouvertes.fr/tel-00481443v1 http://cat.inist.fr/?aModele=afficheN&cpsidt=194412 https://dx.doi.org/10.5281/zenodo.634010 Open Access Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 info:eu-repo/semantics/openAccess CC-BY Langmuir waves Incoherent Scattering Wave dispersion relation Ionosphere Electron velocity distribution function Suprathermal electron Heat flow Text Thesis article-journal ScholarlyArticle 1998 ftdatacite https://doi.org/10.5281/zenodo.51817 https://doi.org/10.5281/zenodo.634010 2021-11-05T12:55:41Z This work presents a study of the electron plasma lines observed by the incoherent scatter radar EISCAT. The work is focusing on two parts. On one hand, the design of a plasma line experiment for the EISCAT system with an improved spatial resolution. On the other hand, the comparison of the plasma line data collected with the EISCAT radar with an improved model for the intensity and the Doppler frequency shift of the plasma lines. In order to improve the spatial resolution of the plasma line experiment we have designed the first experiment that implements the recent technique of alternating code. The experiment has been run successfully with an altitude resolution of 3 km as opposed to 40–50 km obtained with the conventional techniques. Because it is very difficult to construct a self-consistent model of the velocity distribution function encompassing all of the relevant energy range, we have made an ad hoc model by separating the distribution into two parts: the thermal and the supra-thermal population. The thermal population is represented by the Spitzer function that takes into account the effect of an electric field and/or a temperature gradient. The supra-thermal population is derived from the angular energy flux of the supra-thermal electrons calculated by a numerical electron transport model. A numerical code has been developed to calculate the dielectric function and the reduced one-dimensional velocity distribution for any arbitrary two-dimensional velocity distribution which are needed to model the intensity and the Doppler frequency shift of the plasma lines. We have been able to reproduce peculiar features of the intensity as well as the Doppler shift of the plasma lines with data collected with the EISCAT VHF radar. Especially, two sharp peaks in the supra-thermal distribution were identified as the signature of photo-ionisation of N 2 and O and were observed in the measured data. The effect of the temperature gradient—which produces a decisive correction to the Doppler shift of the plasma lines—was taken into account more accurately than previously by numerical evaluation of the singular integrals rather than by the use of the first terms of a series expansion as done in other studies. This is important because it has allowed a model for the first time to reproduce accurately the intensity and the Doppler shift of the plasma line as measured by actual experiment. Thesis EISCAT DataCite Metadata Store (German National Library of Science and Technology) Langmuir ENVELOPE(-67.150,-67.150,-66.967,-66.967) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
Langmuir waves Incoherent Scattering Wave dispersion relation Ionosphere Electron velocity distribution function Suprathermal electron Heat flow |
spellingShingle |
Langmuir waves Incoherent Scattering Wave dispersion relation Ionosphere Electron velocity distribution function Suprathermal electron Heat flow Guio, Patrick Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
topic_facet |
Langmuir waves Incoherent Scattering Wave dispersion relation Ionosphere Electron velocity distribution function Suprathermal electron Heat flow |
description |
This work presents a study of the electron plasma lines observed by the incoherent scatter radar EISCAT. The work is focusing on two parts. On one hand, the design of a plasma line experiment for the EISCAT system with an improved spatial resolution. On the other hand, the comparison of the plasma line data collected with the EISCAT radar with an improved model for the intensity and the Doppler frequency shift of the plasma lines. In order to improve the spatial resolution of the plasma line experiment we have designed the first experiment that implements the recent technique of alternating code. The experiment has been run successfully with an altitude resolution of 3 km as opposed to 40–50 km obtained with the conventional techniques. Because it is very difficult to construct a self-consistent model of the velocity distribution function encompassing all of the relevant energy range, we have made an ad hoc model by separating the distribution into two parts: the thermal and the supra-thermal population. The thermal population is represented by the Spitzer function that takes into account the effect of an electric field and/or a temperature gradient. The supra-thermal population is derived from the angular energy flux of the supra-thermal electrons calculated by a numerical electron transport model. A numerical code has been developed to calculate the dielectric function and the reduced one-dimensional velocity distribution for any arbitrary two-dimensional velocity distribution which are needed to model the intensity and the Doppler frequency shift of the plasma lines. We have been able to reproduce peculiar features of the intensity as well as the Doppler shift of the plasma lines with data collected with the EISCAT VHF radar. Especially, two sharp peaks in the supra-thermal distribution were identified as the signature of photo-ionisation of N 2 and O and were observed in the measured data. The effect of the temperature gradient—which produces a decisive correction to the Doppler shift of the plasma lines—was taken into account more accurately than previously by numerical evaluation of the singular integrals rather than by the use of the first terms of a series expansion as done in other studies. This is important because it has allowed a model for the first time to reproduce accurately the intensity and the Doppler shift of the plasma line as measured by actual experiment. |
format |
Thesis |
author |
Guio, Patrick |
author_facet |
Guio, Patrick |
author_sort |
Guio, Patrick |
title |
Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
title_short |
Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
title_full |
Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
title_fullStr |
Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
title_full_unstemmed |
Studies of ionospheric parameters by means of electron plasma lines observed by EISCAT |
title_sort |
studies of ionospheric parameters by means of electron plasma lines observed by eiscat |
publisher |
Zenodo |
publishDate |
1998 |
url |
https://dx.doi.org/10.5281/zenodo.51817 https://zenodo.org/record/51817 |
long_lat |
ENVELOPE(-67.150,-67.150,-66.967,-66.967) |
geographic |
Langmuir |
geographic_facet |
Langmuir |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
http://munin.uit.no/handle/10037/2976 https://tel.archives-ouvertes.fr/tel-00481443v1 http://cat.inist.fr/?aModele=afficheN&cpsidt=194412 http://munin.uit.no/handle/10037/2976 https://tel.archives-ouvertes.fr/tel-00481443v1 http://cat.inist.fr/?aModele=afficheN&cpsidt=194412 https://dx.doi.org/10.5281/zenodo.634010 |
op_rights |
Open Access Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5281/zenodo.51817 https://doi.org/10.5281/zenodo.634010 |
_version_ |
1766400074137468928 |