Observations of Small-scale Magnetic Reconnections within a Magnetic Flux Rope in Earth’s Magnetosheath

Abstract

The small-scale magnetic reconnection, which has been observed in turbulent plasma, is detected in the interior regions of an ion-scale flux rope in the magnetosheath. Reconnecting current sheets are configured with a nearly symmetric inflow boundary condition and a large guide field of six times the asymptotic field. The evidence of ongoing reconnection is consistent with the standard reconnection model, except no ion flow is detected. In this study, the electron shear flow near the current sheets allows the reconnections to occur. Strong dissipation with these reconnections indicate that electromagnetic energy can be effectively transformed into electron heating and kinetic energy. In particular, the small-scale reconnections do not result in an increase in high-energy electrons, but are responsible for an increase in electron flux over a lower energy range of 100–200 eV. Observations indicate that small-scale reconnection is very common and provides an important channel for energy dissipation in the magnetosheath plasma.