Global Simulation of the Jovian Magnetosphere: Transitional Structure From the Io Plasma Disk to the Plasma Sheet

摘要

Jupiter has a strong magnetic field, and a huge magnetosphere is formed through the solar wind-Jupiter interaction. The generated magnetosphere-ionosphere system is reproduced based on the 9-component Magnetohydrodynamics (MHD) and the current conservation in the ionosphere. Assuming Io plasma emission rate 1.4 t/sec, this paper reproduces self-consistently global magnetic configuration, generations of the field-aligned current (FAC) and aurora, formation of the Io plasma disk at 8-20 RJ, plasma corotation, instability in the plasma disk, transition from the Io plasma disk to the plasma sheet at 20-150 RJ, and the plasmoid ejection. The rotating Io plasma in the disk forms instabilities that promotes radial diffusion. H~+ is supplied from the ionosphere along high-latitude magnetic field lines and mixed with heavy ions around 15-20 RJ. Beyond 20 RJ, mixed plasma diffuses further outward by the centrifugal force that can exceed magnetic tension. In the ionosphere, the main oval occurs at 13.7°-15.5° colatitude. The Io disk is inner side of magnetic field lines traced from the low-latitude edge of the main oval. Along magnetic field lines, the main oval is mapped from the outer edge of the Io disk to the entire plasma sheet accompanying rotation delay. Due to the corotation limit, convection is accompanied by plasmoid ejection. Back reaction of plasmoid ejection affects even transport process in the Io disk. The downward FAC occurs in the polar cap showing variability. The region of externally driven Dungey convection seems quite narrow.