A document by Yingdong Jia. Click on the document to view its contents.

Magnetic flux ropes are ubiquitous in various space environments, including the solar corona, interplanetary solar wind, and planetary magnetospheres. When these flux ropes intertwine, magnetic reconnection may occur at the interface, forming disentangled new ropes. Some of these newly formed ropes contain reversed helicity along their axes, diverging from the traditional flux rope model. We introduce new observations and interpretations of these newly formed flux ropes from existing Hall Magnetohydrodynamics model results. We first examine the time-varying local magnetic field direction at the impact interface to assess the likelihood of reconnection. Then we investigate the electric current system to describe the evolution of these structures, which potentially accelerate particles and heat the plasma. This study offers novel insights into the dynamics of space plasmas and suggests a potential solar wind heating source, calling for further synthetic observations.

Flux transfer events (FTEs), as flux ropes (FRs), are considered key agents for solar wind energy to enter the terrestrial magnetosphere. Recent observations identify entangled flux tubes that collide and pull against each other. Reconnection occurs to disentangle and produce a new pair of flux ropes with different connectivity. In this paper, we examine how such an entanglement process evolve in time by comparing 17 entanglements observed by the Magnetospheric Multiscale (MMS) mission. The By-dominated interplanetary magnetic field (IMF) distribution of the entangled tubes agrees with previous findings. We have identified three evolutionary stages characterized by the magnetic field and pressure enhancement. Our study confirms the flux rope nature of these events and explains how a disparate pair of ropes is formed from two entangled flux tubes, each initially connected to a different hemisphere of the magnetosphere.

At the Earth’s magnetopause, flux tubes observed by the Magnetospheric Multiscale (MMS) spacecraft in “entangled” pairs have been interpreted as a precursory stage to the formation of a new pair of flux ropes by magnetic reconnection, of which one reconnected rope joins the magnetosphere. Understanding the connectivity of these tubes before and after the entanglement is essential to understanding the transport of particles and energy between the magnetosphere and the solar wind. In this paper, we use a three-dimensional Hall MHD model to simulate the interaction of two entangled flux tubes in the ambient plasma. Four types of interactions are simulated: Two types of magnetic field geometry (flux tube-flux tube, and flux rope-flux rope) are tested separately, each under two different boundary conditions that drive the interaction. With one type of boundary condition, magnetic reconnection transforms the two tubes/ropes into new pairs. The process is performed under plasma conditions comparable to those of such events identified in recent MMS observations. The detailed 3-D evolution is shown at representative stages, with key parameters shown across the entanglement interface. The shape of the central current sheet and evolution of magnetic field curvature are also discussed. Our study supports the feasibility of reconnection between entangled flux tubes, recognizes the importance of ambient plasma conditions for the completion of such processes, and quantifies how such structures evolve to modify the solar wind-geomagnetic field interaction. In addition, this model is applicable to flux rope interactions in the solar corona.