Observations of small scale electrostatic structures close to the magnetopause by Cluster-Whisper.
Résumé
Intense and localized bursts of electrostatic emissions at frequencies close to the local electron plasma frequency were observed close to the magnetopause, on the magnetospheric side, by the Whisper instruments on board the Cluster spacecraft. The data combined from the four points measurements have shown, on one example, that the size of the structure can be of a few tens of kilometers. We present here the results of the search for such structures in the Cluster data, as well as their main characteritics. We show that they are commonly observed in this region and discuss their possible origin.