Resolution de l'equation de transport et applications dans le plasma ionospherique

Two major sources of ionization occur in the high latitude ionosphere : the electrons created by solar photo-ionization, and the precipitated electrons. The transport equation describing their evolution is described, and a model of resolution of this equation is discussed and tested. Using this program, we compute the diurnal secondary electron production for different solar fluxes, and we propose a simple mathematical model of it. Then, we study the thermal electron energy ,budget, using a precipitated flux. The budget equation determines the balance between the heating rate, the cooling rate, and the heat conduction. Using intensively the measurements (radar EISCAT and satellite VIKiNG), we show that in our actual knowledge of the electron cross-sections, this budget is correctly satisfied. The effect of ion precipitations is shown during one of the spacecraft orbit.