Etude de l'émission et de la propagation du Continuum terrestre à partir des données des satellites Cluster

摘要

Continuum radiation is an electromagnetic wave of weak intensity, steady in time. This radiation has been observed by several satellites in all regions of the magnetosphere and in the solar wind. Missions as Voyager and Ulysses have shown that Continuum exists in the environment of all explored magnetized planets. Hence, Continuum is a classical astronomical phenomenon. A study of the terrestrial Continuum radiation emission and of its propagation is developed in this dissertation. This study is based on data from the WHISPER instrument on board the Cluster mission. This mission is a constellation of four identical satellites. The tetrahedral configuration of the satellites allows a spatial-temporal study of the structures they cross. Using data of a constellation of four identical satellites yields new pieces of information, especially on emission stability, beam width and source position. These pieces of information allow specific tests of the existing generation mechanisms. The spectral characteristics give access in one hand to the local shape of the emitting surface, and on the other hand on the stability in time of this surface. Lastly, the resolution in time and in frequency of the WHISPER instrument allows a study of the spectral characteristics of Continuum radiation and of their evolution in time. In summary, this PhD thesis puts forwards new pieces of information about the generation mechanism, position and extension of the source, shape of the emitting surface and evolution of spectral signature evolution during the propagation.