Two different types of plasmoids in the plasma sheet: Cluster multisatellite analysis application

The fine magnetic field structure of two successive plasmoids previously reported is investigated by magnetic rotation analysis using four Cluster satellite data. Between these two plasmoids, opposite trends of curvature radius (R_c) variations of the magnetic field lines from the boundary to the inner part are found. The different variations of R_c reflect that the two plasmoids have different magnetic configurations. The electric current density distributions for both plasmoids are found distinct. The B_y increase and abundant field-aligned currents in the narrow core region of the first plasmoid indicate that a possible magnetic flux rope (MFR) core exists inside. The results indicate that the first observed plasmoid is of a magnetic loop (ML) type (with possible MFR core) and the second plasmoid is of a magnetic flux rope (MFR) type. The coexistence of ML and MFR in the near-Earth plasma sheet may imply that multiple X line reconnection can occur by either an antiparallel or a component-parallel way. Key Points Two plasmoids have contrary variation of curvature radius of magnetic field lineDifferent magnetic configuration in ML,MFR due to different current distributionResults can help differentiate between ML and MFR without prominent core field