Asymmetric 3-D Kelvin–Helmholtz instability
Presentation Type
Poster
Presenter Format
In Person Meeting Talk
Topic
Fundamental Processes in Comparative Magnetospheres
Start Date
10-5-2022 5:30 PM
Abstract
It has been demonstrated that the Kelvin–Helmholtz (KH) instability plays an important role in the solar-wind-magnetosphere coupling process for different planets. Driven by a large shear flow, the KH instability can transport the mass, magnetic flux, and energy between the magnetosheath and magnetosphere (or ionosphere). Meanwhile, strong density, temperature, and magnetic field asymmetry often present between the magnetosheath and magnetosphere, which also affects the KH onset condition, and consequently affect the transport processes. It has been shown that the strong plasma beta asymmetry across the current layer will compress the magnetic reconnection rate. Notice that the strong plasma beta asymmetry also indicates a strong asymmetric magnetic field. In this study, we use MHD simulation illustrate that the reconnection rate during the nonlinear interaction between KH instability and reconnection is still higher than the typical magnetic reconnection rate, even with a strong plasma beta asymmetry. However, the variation of reconnection rate as the function of the magnetic asymmetry is still consistent with Cassak-Shay’s scaling. Meanwhile, in the nonlinear stage of the KH instability under Northward IMF condition, a large net mass transport rate occurs only when there is a strong flux content (i.e., ∝ρ/B ) asymmetry via the double-middle-latitude-reconnection (DMLR) process. As such, it is of interest to investigate the influence of the magnetosheath-magnetosphere asymmetry on the nonlinear interaction between the KH instability and magnetic reconnection. This presentation estimates the mass and flux transport rate at different IMF conditions by using MHD with test particle simulations. It also shows how perpendicular to parallel temperature anisotropy will be formed in the 3-D KHI in presence of temperature asymmetry across the magnetopause, due to the change of the magnetic field topology via DMLR. We will also compare the simulation results with recent in-situ spacecraft observations.
Asymmetric 3-D Kelvin–Helmholtz instability
It has been demonstrated that the Kelvin–Helmholtz (KH) instability plays an important role in the solar-wind-magnetosphere coupling process for different planets. Driven by a large shear flow, the KH instability can transport the mass, magnetic flux, and energy between the magnetosheath and magnetosphere (or ionosphere). Meanwhile, strong density, temperature, and magnetic field asymmetry often present between the magnetosheath and magnetosphere, which also affects the KH onset condition, and consequently affect the transport processes. It has been shown that the strong plasma beta asymmetry across the current layer will compress the magnetic reconnection rate. Notice that the strong plasma beta asymmetry also indicates a strong asymmetric magnetic field. In this study, we use MHD simulation illustrate that the reconnection rate during the nonlinear interaction between KH instability and reconnection is still higher than the typical magnetic reconnection rate, even with a strong plasma beta asymmetry. However, the variation of reconnection rate as the function of the magnetic asymmetry is still consistent with Cassak-Shay’s scaling. Meanwhile, in the nonlinear stage of the KH instability under Northward IMF condition, a large net mass transport rate occurs only when there is a strong flux content (i.e., ∝ρ/B ) asymmetry via the double-middle-latitude-reconnection (DMLR) process. As such, it is of interest to investigate the influence of the magnetosheath-magnetosphere asymmetry on the nonlinear interaction between the KH instability and magnetic reconnection. This presentation estimates the mass and flux transport rate at different IMF conditions by using MHD with test particle simulations. It also shows how perpendicular to parallel temperature anisotropy will be formed in the 3-D KHI in presence of temperature asymmetry across the magnetopause, due to the change of the magnetic field topology via DMLR. We will also compare the simulation results with recent in-situ spacecraft observations.
