Using measurements of the Magnetospheric Multiscale mission in the magnetotail from −24 to −15R E, we identified 40 ion Bursty Bulk Flow events (BBFs) and investigated the electron behaviors during these BBFs. The ion flows peaked near the center of the plasma sheet and had a sharp flow boundary. The electron-flow profile is distinct from the ion flows of the BBFs. Inside the BBFs, the strongest Earthward electron flows are observed in the ion flow boundary, away from the current sheet center. Farther away from the peak of the Earthward electron flows, the tailward electron flows are observed in the edges of the ion flows, are mainly field-aligned with low energy, and are stronger than the Earthward flows. It seems that the tailward low-energy electrons are energized at some places tailward of the spacecraft and then ejected Earthward, consistent with the magnetic reconnection scenario in the magnetotail. We suggest this has implications for our understanding of astrophysical jets.

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<p>By measurements of the Magnetospheric Multiscale (MMS) mission in the magnetotail from -24 to -15 R<sub>E</sub> , we identified 40 ion Bursty Bulk Flow events (BBFs) and investigated the electron behaviors during these BBFs. The ion flows peaked near the center of the plasma sheet and had a sharp flow boundary. The electron flow profile is distinct from the ion flows of the BBFs. Inside the BBFs, the strongest earthward electron flows are observed in the ion flow boundary, away from the current sheet center. Further away from the peak of the earthward electron flows, the tailward electron flows are observed in the edges of the ion flows, are mainly field-aligned with low energy, and are stronger than the earthward flows. It seems that the tailward low-energy electrons are energized at some places tailward of the spacecraft and then ejected towards Earth, consistent with the magnetic reconnection scenario in the magnetotail. The implication to the understanding of the astrophysical jets is suggested.</p>

The reconnection in nearly symmetric inflow boundary conditions with a strong guide field of three is detected at the magnetopause. The thin current sheet was well resolved by the Magnetospheric Multiscale mission, which revealed that there is a pair of low-density separatrices and a pair of higher-density separatrices. Electron flow is accelerated toward the X-line along the low-density side and ejected out along the higher-density side. All flows are super-Alfvénic, but the outflow velocity is much lower than the inflow velocity. It is further shown that the width of higher-density separatrices is about twice that of the low-density separatrices. Significant and opposite electric field activity is observed on both sides of the current sheet. Our observations show that the separatrix regions between the two sides of strong-guide-field reconnection are significantly different in structure and plasma properties, which in turn affect the acceleration and heating of electrons.