Ion Kinetics in the Solar Wind: Coupling Global Expansion to Local Microphysics

We discuss selected ion kinetic processes relevant in the context of the expanding solar wind. We focus on the role of wave-wave and wave-particle interactions, plasma instabilities and Coulomb collisions on the overall kinetic evolution of ions. We review recent results from the hybrid expanding box model, which enables the coupling of the large scale effects of the solar wind expansion to the microscale kinetics of ions. We discuss how different plasma processes develop and influence each other during the expansion, as well their role in the shaping of ion distribution functions, and we compare the simulation results with the observed trends in the solar wind.