Electron Jet Detected by MMS at Dipolarization Front

Abstract

Abstract Using MMS high‐resolution measurements, we present the first observation of fast electron jet ( V e ~2,000 km/s) at a dipolarization front (DF) in the magnetotail plasma sheet. This jet, with scale comparable to the DF thickness (~ 0.9 d i ), is primarily in the tangential plane to the DF current sheet and mainly undergoes the E × B drift motion; it contributes significantly to the current system at the DF, including a localized ring‐current that can modify the DF topology. Associated with this fast jet, we observed a persistent normal electric field, strong lower hybrid drift waves, and strong energy conversion at the DF. Such strong energy conversion is primarily attributed to the electron‐jet‐driven current ( E ⋅ j e ≈ 2 E ⋅ j i ), rather than the ion current suggested in previous studies.