Energy exchanges between particles and ion-scale waves and structures in space plasmas with multi-scale explorations: insights from numerical simulations

 

The crossover between fluid and ion scales in space plasmas plays a crucial role in the overall energization of the system and it’s where most of the energy exchanges between fields and particles take place. At these scales, turbulent dynamics cascading from larger fluid scales and structures from local ion microphysics typically coexist, leading to still unexplored couplings. Multi-point/multi-scale measurements  are then required to fully capture this complex dynamics in situ. 7-point measurements by Plasma Observatory (PMO) in the Earth’s magnetosphere environment offer the opportunity to explore this dynamics and the fluid-ion scale coupling for the first time, in plasma environments with different typical characteristic parameters  and dynamical regimes: e.g. solar wind, magnetosheath, magnetotail.

In this presentation, we review numerical simulations of plasma turbulence focussing on the transition from fluid to ion scales and its coexistence with ion kinetic processes, in particular micro-instabilities (e.g. mirror, firehose, ion-drift). This include the role played by pressure-strain interactions in controlling the turbulent cascade rate and modulating energy exchanges in the plasma, and how these aspects could be captured for the first time by a constellation like PMO.

We address the interplay between these processes and highlight the different spatial and temporal scales involved. As waves and structures from these processes are typically anisotropic, different characteristic scales can be observed, depending on the direction of the sampling, thus making multi-point measurements essential to fully capture them.