Kinetic Alfvén Waves From Magnetotail to the Ionosphere in Global Hybrid Simulation Associated With Fast Flows

Abstract

We have used the Auburn Global Hybrid Code in 3‐D to study the generation, dynamics, and global structure of kinetic Alfvén waves (KAWs) from the magnetotail to the ionosphere. Our results show that KAWs are generated in magnetic reconnection in the plasma sheet, located around fast flows, and carrying transverse electromagnetic perturbations, parallel Poynting fluxes, parallel currents, and parallel electric field. Overall, shear Alfvénic turbulent spectrum is found in the plasma sheet. The KAWs are shear Alfvén waves possessing short perpendicular wavelength with k⊥ρi∼1, where k⊥ is the perpendicular wave number and ρi the ion Larmor radius. The KAWs are identified by their dispersion relation and polarizations. The structures of these KAWs embedded in the plasma sheet are also revealed by placing a virtual satellite in the tail. In order to understand whether the Poynting fluxes carried by the shear Alfvén waves/KAWs in the plasma sheet can be carried directly along field lines to the ionosphere, we have tracked the wave propagation from the plasma sheet to the ionosphere. It is found that in front of the flow‐braking region, the structure and strength of the shear Alfvén waves are significantly altered due to interaction with the dipole‐like field, mainly by the flow shear associated with the azimuthal convection. Also in front of the dipole‐like field region, ion kinetic effects (Hall effects) lead to the generation of additional pairs of KAWs. As such, the generation and transport of the shear Alfvén waves/KAWs to the ionosphere are illustrated for the first time in a comprehensive manner on the global scale.

Kelvin–Helmholtz‐Related Turbulent Heating at Saturn's Magnetopause Boundary

“…However, in the case of kinetic Alfvén waves, the Walen relation for scales much larger than the electron inertial length is (L. Cheng et al, 2020)  …”

Thermal electron anisotropy driven by kinetic Alfven waves in the Earth's magnetotail

“…KAWs as a natural mode of Alfven waves in hot ion plasma (Stasiewicz et al, 2000) are suggested to be generated by several different mechanisms, e.g., mode conversion (Hasegawa and Chen, 1975;Hasegawa, 1976;Lin et al, 2012;Johnson and Cheng, 1997), phase mixing (Guo et al, 2015) and magnetic reconnection (Chaston et al, 2005(Chaston et al, , 2009Liang et al, 2016;Wang et al, 2019b;Cheng et al, 2020). These waves are believed to be responsible for energy transfer from the magnetotail to 10 -1 10 0 10 1 10 2…”

Magnetotail‐Inner Magnetosphere Transport Associated With Fast Flows Based on Combined Global‐Hybrid and CIMI Simulation

“…The solar wind ion temperature is T 0 = 10 eV. This case has previously been studied by Lin, Wang, et al (2014); ; L. Cheng, Lin, et al (2020) for various properties of fast flows in the magnetotail using ANGIE3D. Figure 1 shows the global view of magnetic field strength B at simulation time t = 00:58:27, approximately 1 h after the impact of the solar wind on the magnetosphere, obtained from the global hybrid simulation, together with some typical magnetic field lines (orange solid line).…”

“…(2014) and L. Cheng, Lin, et al. (2020). A typical time step interval for advancing particles is , within which a subcycling of 10 steps is applied to the magnetic field update.…”