Multi-instrument study of the hourly pulsations in Saturn’s magnetosphere

The in-situ exploration of the magnetospheres of Jupiter and Saturn has revealed various pulsed phenomena, some of them being periodic. In Saturn’s magnetosphere, several studies have reported pulsations with a periodicity of around one hour in the measurements of charged particle fluxes, plasma wave emissions, magnetic field strength and auroral emission brightness. This thesis reports the first multi-instrument study of these hourly pulsations using data sets of several instruments on board the Cassini spacecraft orbiting around Saturn since 2004. A 10-year survey of the quasi-periodic hourly pulsations in the energetic electron flux has been achieved. A statistical analysis of these pulsations together with the investigation of simultaneous pulsations in the low-frequency radio emissions and in the magnetic field provided information about the source of the pulsed electrons. Finally, the magnetospheric process triggering the electron pulsations is widely discussed on the basis of the observation of hourly brightening of auroral spots and the existence of pulsed electrons in the vicinity of the magnetopause.