UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-22 1:44
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Conference: Bucharest University Faculty of Physics 2010 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
A parametric study of the supersonic expansion of the solar corona using the kinetic exospheric approach based on Lorentzian velocity distribution function


Authors:
R. Damian (1), G. Voitcu (2), M. Echim (2)(3)


Affiliation:
(1) Faculty of Physics, University of Bucharest, Magurele, Romania

(2) Institute for Space Sciences, Magurele, Romania

(3) Belgian Institute for Space Aeronomy, Brussels, Belgium


E-mail
damian_raluk@yahoo.com


Keywords:
solar wind, exospheric model, Lorentzian velocity distribution function, exobase


Abstract:
The solar wind is the supersonic expansion of the hot corona into the interplanetary space. It is a plasma essentially made of electrons and protons with a small proportion of heavier ions in addition. In this paper we perform a parametric study based on exospheric model of the solar wind developed by Lamy et al. (2003). The exobase is the boundary that separates collision dominated plasma by a fully collisionless regime, i.e. the exosphere. The model of Lamy et al. (2003) considers a nonmonotonic total potential energy for the protons. The velocity distribution function (VDF) at the exobase is given by a Lorentzian (kappa) distribution for electrons, while the VDF of protons is given by a Maxwellian distribution. The model is based on a single exobase for both electrons and protons. In this study we investigate the influence of several model parameters on the solar wind macroscopic parameters, e.g. number density, bulk velocity, parallel and perpendicular temperature. We study the effects of changing the kappa index of the electron VDF, as well as of the electron temperature at the exobase and the exobase altitude. Our results show that a faster solar wind is obtained when the value of the kappa index for electrons decrease. Also, the solar wind speed increases when the exobase is located deeper in the corona. On the other hand, it is shown that by increasing the electron temperature at the exobase, the solar wind bulk velocity also increases.