Structure of exhaust jets produced by magnetic reconnection localized in the out-of-plane direction

摘要

abstract_textpThree-dimensional electromagnetic particle-in-cell simulations are used to investigate the structure of exhaust jets produced by magnetic reconnection localized in the out-of-plane direction. The localized reconnection is produced by periodically blocking the cross-tail current density, a procedure that has effects analogous to those produced by the assumption of a region of anomalous resistivity in fluid treatments of reconnection. The width of the blocking region is varied between 4 and 24d(i), where d(i) is the ion inertial length. After an initial displacement in the electron-drift direction, the jet front undergoes a marked expansion in the ion-drift direction, reaching a total cross-tail width of 15-20d(i) regardless of the initial width. The jet front breaks up into small-scale finger structures of the order of 1-2d(i) in width, which appears to be due to the action of the ballooning/interchange instability. Ahead of the front, the ion pressure P-ixx is increased due to reflection of ions from the moving front and the penetration of high-speed ions in the jet through the front. The ion temperature T-ixx exhibits a minimum within the front, while the electron temperature is enhanced in the front. The properties of the reconnection-generated fronts are compared and contrasted with those of interchange heads produced by a decreasing entropy profile./p/abstract_text