Spatial Scales of Super Thin Current Sheets with MMS Observations in the Earth’s Magnetotail

We studied the magnetic configuration and determined the spatial scales of the super thin current sheets observed by MMS in the Earth’s magnetotail during the propagation of a high-velocity plasma bulk flow directed tailward. A new method proposed for the determination of the half-thickness of super thin current sheets uses four-point measurements of the magnetic field by MMS in burst mode. We found that in many cases the half-thickness of super thin current sheets are only a few (1–5) gyroradii of thermal electrons. Electrons carry approximately 70% of the current density in such current sheets, and the current density is several times higher than the ion current density in the current sheet.