Proton Kinetic Effects in Vlasov and Solar Wind Turbulence

TL;DR

This study uses Hybrid Vlasov-Maxwell simulations to explore how proton temperature anisotropy relates to plasma beta and turbulence structures, aligning with solar wind observations and highlighting the role of intermittency in plasma dynamics.

Contribution

It demonstrates the ability of HVM simulations to reproduce observed proton temperature anisotropy patterns and links kinetic effects to turbulence intermittency in plasma.

Findings

Proton temperature anisotropy depends on plasma beta and fluctuation levels.

Anisotropy correlates with magnetic and flow intermittency.

Simulation results align with spacecraft solar wind data.

Abstract

Kinetic plasma processes have been investigated in the framework of solar wind turbulence, employing Hybrid Vlasov-Maxwell (HVM) simulations. The dependency of proton temperature anisotropy T_{\perp}/T_{\parallel} on the parallel plasma beta \beta_{\parallel}, commonly observed in spacecraft data, has been recovered using an ensemble of HVM simulations. By varying plasma parameters, such as plasma beta and fluctuation level, the simulations explore distinct regions of the parameter space given by T_{\perp}/T_{\parallel} and \beta_{\parallel}, similar to solar wind sub-datasets. Moreover, both simulation and solar wind data suggest that temperature anisotropy is not only associated with magnetic intermittent events, but also with gradient-type structures in the flow and in the density. This connection between non-Maxwellian kinetic effects and various types of intermittency may be a key point for understanding the complex nature of plasma turbulence.