Soutenance de thèse d'Alexander Vinogradov 5/12/2023, 15h, Meudon

Annonce transmise par Olga Alexandrova (LESIA)

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

Date: 5 December 2023, 15:00 (CET)

Location: Observatoire de Paris, Amphithéâtre Évry Schatzman, Bâtiment 18, 5 Place Jules Janssen, Meudon, France

https://www.youtube.com/channel/UCzPLngWE_6JVuJ4szh8U-RQ

Language: English

Jury:
Annick POUQUET, LASP, University of Colorado Boulder, (Referee)
Marco VELLI, EPSS, UCLA (Referee)
Thiery PASSOT, LAGRANGE, Observatoire de la Côte d'Azur (Examiner)
Laurence REZEAU, LPP, Observatoire de Paris (President)
Pierre LESAFFRE, Laboratoire de Physique, ENS (Examiner)
Olga ALEXANDROVA, LESIA, Observatoire de Paris (Supervisor)
Pascal DEMOULIN, LESIA, Observatoire de Paris (Invited)
Anton ARTEMYEV, IGPP, UCLA (Invited)

Abstract:
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.