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Fonctions de distribution de vitesses non-maxwelliennes dans le plasma ionosphérique et application à la mesure par diffusion incohérente

Abstract : In magnetically perturbed periods, we have to consider a non-Maxwellian ion-velocity distribution-function in order to correctly estimate the ionospheric parameters of the auroral region measured by incoherent scatter. We have compared two models of non-Maxwellian distribution function: the polynomial expansion approximation which is a solution of Boltzmann equation, and a numerical distribution based on a Monte Carlo method. Both approaches lead to identical results for electric fields smaller than 100 mV/m and for the two ions species O+ and NO+. The analytical distribution has been introduced in the EISCAT's analysis to study the auroral ionosphere during periods of electric fields up to 100 m V /m. First, this new analysis has been tested on several sets of simulations with a sensitivity study to the models used. In a second time, we have studied spectra which present non-Maxwellian characteristics, and we have determined the ion composition of the ionosphere when high electric fields occur. Finally, with a last set of real data, we have estimated quantitatively the error that we make when we analyse non-Maxwellian spectra with a "Maxwellian" interpretation in the case of an ionosphere composed of molecular ions.
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https://tel.archives-ouvertes.fr/tel-00724945
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Submitted on : Thursday, August 23, 2012 - 1:22:45 PM
Last modification on : Friday, November 6, 2020 - 4:05:31 AM
Long-term archiving on: : Saturday, November 24, 2012 - 2:31:02 AM

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Patricia Gaimard. Fonctions de distribution de vitesses non-maxwelliennes dans le plasma ionosphérique et application à la mesure par diffusion incohérente. Planétologie et astrophysique de la terre [astro-ph.EP]. Université Joseph-Fourier - Grenoble I, 1996. Français. ⟨tel-00724945⟩

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