Zoom link :
https://cnrs.zoom.us/j/95003883304?pwd=MI0B5WLYiGZlzo3oAZUl5TAu4fta6q.1
Abstract :
The Parker Solar Probe mission provides new insights on the nature of turbulence in regions where the solar wind is still forming and being energized. In situ observations near 11.4 Solar Radii illuminate the multiscale dynamics of the solar wind, showing how turbulent energy injected at large MHD scales cascades down to ion and electron kinetic scales, where the energy dissipation occurs. Understanding the transfer of magnetic energy across scales and quantifying how much turbulent energy reaches kinetic scales matters for plasma heating and particle acceleration.
Using PSP high-cadence measurements, I will summarize spectral evidence for an inertial range with a power law spectrum that breaks near ion characteristic scales ; beyond that break the spectrum steepens as kinetic processes becomes dominant. I will highlight signatures of coherent structures revealed by wavelet transform and higher order statistics. On one hand, turbulence is not purely random. Localized events such as current sheets or Alfvén vortices feature intermittent fluctuations and non-Gaussian statistics. On the other hand, at ion scales, nonthermal features in particle distributions can drive kinetic instabilities that generate ion cyclotron waves. In this case, the turbulent energy transfer becomes reduced, and intermittency is suppressed around these scales. These findings have implications for mapping the macroscopic cascade to the microscopic dissipation that contribute to solar wind acceleration and heating.
