Turbulent mass transfer caused by vortex induced reconnection in collisionless magnetospheric plasmas

Abstract

Magnetic reconnection is believed to be the main driver to transport solar wind into the Earth’s magnetosphere when the magnetopause features a large magnetic shear. However, even when the magnetic shear is too small for spontaneous reconnection, the Kelvin–Helmholtz instability driven by a super-Alfvénic velocity shear is expected to facilitate the transport. Although previous kinetic simulations have demonstrated that the non-linear vortex flows from the Kelvin–Helmholtz instability gives rise to vortex-induced reconnection and resulting plasma transport, the system sizes of these simulations were too small to allow the reconnection to evolve much beyond the electron scale as recently observed by the Magnetospheric Multiscale (MMS) spacecraft. Here, based on a large-scale kinetic simulation and its comparison with MMS observations, we show for the first time that ion-scale jets from vortex-induced reconnection rapidly decay through self-generated turbulence, leading to a mass transfer rate nearly one order higher than previous expectations for the Kelvin–Helmholtz instability.

Energy Conversion by Parallel Electric Fields During Guide Field Reconnection in Scaled Laboratory and Space Experiments

“…(e.g., for Wilder et al, ). Reconnection events driven by KH waves in the magnetopause flank have been proposed to contain multiple flux ropes which might support such dynamics (Eriksson et al, ; Nakamura et al, ; Sturner et al, ). Recent observations in sub‐ion scale current sheets have also observed very large parallel electric fields E || ∼5 E 0 (Phan et al, ); this presents a second idea that large reconnection rates may be linked to reconnection at small spatial scales.…”

On Multiple Hall‐Like Electron Currents and Tripolar Guide Magnetic Field Perturbations During Kelvin‐Helmholtz Waves

“…Based on a 3D fully kinetic simulation of the same MMS KH event on 8 September 2015, Nakamura, Eriksson, et al () and Nakamura, Hasegawa, et al () conducted a study of plasma turbulence and transport across the flank magnetopause due to the KH instability and vortex‐induced magnetic reconnection. MMS burst observations of ion‐scale reconnection exhausts and electron‐scale dissipation associated with an electron diffusion region on 8 September 2015 (Eriksson, Wilder, et al, ) were found to be in good agreement with numerical simulation results on the basis of Vector Particle‐in‐Cell (VPIC), a 3D fully kinetic particle‐in‐cell code (Bowers et al, , ).…”

“…Under certain solar wind conditions, the Kelvin‐Helmholtz (KH) instability creates surface waves and vortices along the flanks of the magnetopause as the high velocity solar wind deflects around the magnetosphere and is believed to be an important source of plasma transport during low magnetic field shear (e.g., Hasegawa et al, ; Miura, ; Nakamura, Eriksson, et al, ; Nakamura, Hasegawa, et al, ). It also provides a near‐Earth region for investigating a form of highly driven, strong guide field reconnection referred to as vortex‐induced reconnection (VIR), which has been proposed to occur under northward interplanetary magnetic field along the magnetopause edges of this surface wave (e.g., Liu & Hu, ; Pu, Yan, & Liu, ).…”

“…The present study will focus on a case of Type 1 VIR coincident with tripolar guide field perturbations as observed for the first time by the MMS satellites across two flank magnetopause current sheets associated with KH waves on 8 September 2015. A three‐dimensional (3D) kinetic simulation of KH wave evolution and vortex‐induced reconnection dedicated to MMS observations on this date (Nakamura, Eriksson, et al, ; Nakamura, Hasegawa, et al, ) will be used to put these new MMS tripolar guide‐field observations in context.…”

Comparison Between Fluid Simulation With Test Particles and Hybrid Simulation for the Kelvin‐Helmholtz Instability

“…Simulation studies from magnetohydrodynamics (MHD) to particle-in-cell (PIC) simulation show a large range of transport rates from 10 9 to 10 10 m 2 /s for Earth's magnetopause environments (Cowee et al, 2009(Cowee et al, , 2010Delamere et al, 2011;Miura, 1984;Ma et al, 2017;Nykyri & Otto, 2001, 2004Nakamura et al, 2017). Simulation studies from magnetohydrodynamics (MHD) to particle-in-cell (PIC) simulation show a large range of transport rates from 10 9 to 10 10 m 2 /s for Earth's magnetopause environments (Cowee et al, 2009(Cowee et al, , 2010Delamere et al, 2011;Miura, 1984;Ma et al, 2017;Nykyri & Otto, 2001, 2004Nakamura et al, 2017).…”