Observatoire de Paris Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Soutenance de thèse d’Alexander Vinogradov le mardi 5 décembre 2023

mercredi 29 novembre 2023

La soutenance de thèse d’Alexander Vinogradov aura lieu le mardi 5 décembre 2023 à 15h00, dans l’amphithéâtre Evry Schatzman du bâtiment 18 .

Elle sera diffusée en direct sur la chaîne YouTube du LESIA :

La thèse sera soutenue en anglais.

Titre de la thèse

"Coherent structures from MHD to sub-ion scales in turbulent solar wind"

Résumé

The solar wind is a rarefied plasma flow propagating away from the Sun and filling the interplanetary space. It is supersonic, super-alfvenic and turbulent. Plasma turbulence in the solar wind manifests itself by large amplitude fluctuations in electromagnetic and velocity fields, in density and temperature. An important ingredient of space plasma turbulence is intermittency, i.e., non-homogeneity of fluctuations related to appearance of localized coherent structures.

We use Parker Solar Probe spacecraft data to study such structures close to the Sun (at 0.17 au). We find coherent structures not only on large magnetohydrodynamic (MHD) scales, but also at kinetic scales. In odd with previous observations, we show that Alfven vortices are dominant events. More rare, planar current sheets are also observed. For the first time, we show that these structures at MHD scales include ion-scale vortices and in their turn, the sub-ion vortices are embedded within the ion-scale ones.