Quantum mechanics

Magnetic field

Scale (ratio)

Substorm

Computational physics

Nuclear physics

Atomic physics

Electric field

Magnetosphere

Geology

Ionosphere

Physics

Electron density

Optics

Environmental science

Geophysics

Electron

Meteorology

Front (military)

Wedge (geometry)

Geophysical Research Letters

Dipolarization front (DF)—a sharp boundary with scale of ion inertial length ( c / ω pi ) in the Earth's magnetotail—can also have fine structures at electron scale ( c / ω pe ). Such electron‐scale structures, determining the local energy conversion, have not been revealed by multispacecraft observations so far, due to the large separation of spacecraft in previous studies. Here we report the first electron‐scale multispacecraft measurements of DF, using data from the recent Magnetospheric Multiscale mission. We find strong parallel currents only in the high‐density side of the DF but strong perpendicular currents across the whole DF. We find no parallel electric fields during the DF interval. Although DF is primarily an energy‐load region (E·J &gt; 0), the electron‐scale currents could lead to a localized energy generation (E·J &lt; 0). Such features are different from those reported in previous multispacecraft studies, where the currents, electric fields, and energy conversion are uniform across the DF; they also shed lights on the study of substorm current wedge, which is crucial in the magnetosphere‐ionosphere coupling.

Electron‐Scale Measurements of Dipolarization Front