Kinetic Space Plasma Physics

Our previous theoretical investigation in the coronal heating and solar wind studies primarily adopted a fluid approach: plasma species are treated as fluids. This approach is indeed very successful in describing the macroscopic behavior of the solar wind plasmas on long time and large spatial scales. A hidden assumption behind the fluid approach is that the velocity distributions of plasma species are gyrotropic. In situ measurements tell us this in general is not the case. This is because the physical nature of resonant wave-particle interaction in a plasma system is kinetic and is on much smaller spatial and temporal scales. As more evidence pointing to the existence of resonant wave particle interaction in the corona and solar wind is starting to emerge, it is inevitable to adopt a kinetic approach to explore the resonant wave-particle interaction process in the solar wind. The proposed research is to use a hybrid simulation and linear plasma wave dispersion relation solver to study the kinetic nature of the nonlinear resonant wave-particle interaction in the extended corona. A 1D hybrid simulation code is being developed for  simulating the ion cyclotron resonance between waves and oxygen ions in the corona, a preliminary result has shown that the velocity distribution of oxygen ions under the impact of ion cyclotron waves will indeed become highly non-Maxwellian and non-gyrotropic.