Over three decades of in-situ observations illustrate that the Kelvin-Helmholtz (KH) instability driven by the sheared flow between the magnetosheath and magnetospheric plasma often occurs on the magnetopause of Earth and other planets under various interplanetary magnetic field (IMF) conditions. It has been well demonstrated that the KH instability plays an important role for energy, momentum, and mass transport during the solar-wind-magnetosphere coupling process. Particularly, the KH instability is an important mechanism to trigger secondary small scale (i.e., often kinetic-scale) physical processes, such as magnetic reconnection, kinetic Alfven waves, ion-acoustic waves, and turbulence, providing the bridge for the coupling of cross scale physical processes. From the simulation perspective, to fully investigate the role of the KH instability on the cross-scale process requires a numerical modeling that can describe the physical scales from a few Earth radii to a few ion (even electron) inertial lengths in three dimensions, which is often computationally expensive. Thus, different simulation methods are required to explore physical processes on different length scales, and cross validate the physical processes which occur on the overlapping length scales. Test particle simulation provides such a bridge to connect the MHD scale to the kinetic scale. This study applies different test particle approaches and cross validates the different results against one another to investigate the behavior of different ion species (i.e., H+ and O+), which include particle distributions, mixing and heating. It shows that the ion transport rate is about 1025 particle s-1, and mixing diffusion coefficient is about 1010 m2s-1 regardless of the ion species. Magnetic field lines change their topology via the magnetic reconnection process driven by the three-dimensional KH instability, connecting two flux tubes with different temperature, which eventually causes anisotropic temperature in the newly reconnected flux.

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Submissions from 2021

Figure 1: Snap shot for the symmetric case and the asymmetric case simulation, Xuanye Ma, Peter Delamere, Katariina Nykyri, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou

Figure 2: The overall dynamical properties for the symmetric case and the asymmetric case, Xuanye Ma, Peter Delamere, Katariina Nykyri, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou

Figure 3: The energy distribution for the symmetric case, Xuanye Ma, Peter Delamere, Heidi Nykyri, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou

Figure 4: Comparison between MHD and particle description from the forward tracing and backward tracing methods in the symmetric case, Xuanye Ma, Peter Delamere, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou

Figure 5: Snap shot for the anisotropic temperature in the symmetric case, Xuanye Ma, Peter Delamere, Heidi Nykyri, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou

Figure 6: Comparison between the symmetric case and asymmetric case in the normalized time scale, Xuanye Ma, Peter Delamere, Heidi Nykyri, Brandon Burkholder, Stefan Eriksson, and Yu-Lun Liou