资源环境科技发展态势分析平台

Three flux ropes associated with near-Earth magnetotail reconnection are analyzed using Magnetospheric Multiscale observations. The flux ropes are Earthward propagating with sizes from similar to 3 to 11 ion inertial lengths. Significantly different axial orientations are observed, suggesting spatiotemporal variability in the reconnection and/or flux rope dynamics. An electron-scale vortex, associated with one of the most intense electric fields (E) in the event, is observed within one of the flux ropes. This E is predominantly perpendicular to the magnetic field (B); the electron vortex is frozen-in with E x B drifting electrons carrying perpendicular current and causing a small-scale magnetic enhancement. The vortex is similar to 16 electron gyroradii in size perpendicular to B and potentially elongated parallel to B. The need to decouple the frozen-in vortical motion from the surrounding plasma implies a parallel E at the structure's ends. The formation of frozen-in electron vortices within reconnection-generated flux ropes may have implications for particle acceleration.

Plain LanguageSummary The release of magnetic energy into particle motion through magnetic reconnection is a key driver of dynamics in the Earth's magnetosphere and other space plasmas. In order to understand how the released magnetic energy is distributed and ultimately heats the particles, a detailed examination of the structures formed by magnetic reconnection is necessary. One common structure produced by reconnection is a twisted magnetic field known as a flux rope. We use new data from the National Aeronautics and Space Administration's Magnetospheric Multiscale satellites to examine both the large-and small-scale properties of three flux ropes associated with a single reconnection event. The results reveal the intrinsic three-dimensional nature of the overall reconnection event, which may stem either from variability at the reconnection site and/or the subsequent dynamics of the structures after they form. Additionally, the high-resolution measurements reveal a new small-scale structure, namely, a vortex of electrons, inside of one of the flux ropes. The presence of such vortices may contribute to accelerating particles and points to the necessity of better understanding the substructure of flux ropes in order to characterize particle energization in magnetic reconnection.