Investigation of Storm-Time Magnetotail and Ion Injection Using 3-D Global Hybrid Simulation
Tuesday, September 29, 2015: 10:30 AM
Yu Lin1, San Lu2, Quanming Lu3, Joseph D Perez1, Xueyi Wang4, Simon Wing5 and Jay Johnson6, (1)Auburn University at Montgomery, Auburn, AL, United States, (2)University of Science and Technology of China, Hefei, China, (3)USTC University of Science and Technology of China, Hefei, China, (4)Auburn University at Montgomery, Montgomery, AL, United States, (5)Johns Hopkins University, Baltimore, MD, United States, (6)Princeton Plasma Physics Lab, Princeton, NJ, United States
Abstract:
Dynamics of the near-Earth magnetotail associated with substorms during a period of extended southward IMF is studied using a three-dimensional (3-D) global hybrid simulation model that includes both the dayside and night side magnetosphere, with physics from the ion kinetic to the global Alfvenic convection scales. It is found that the dayside reconnection leads to the penetration of the dawn-dusk electric field through the magnetopause and thus a thinning of the plasma sheet, followed by the magnetotail reconnection with 3-D, multiple flux ropes. Ion kinetic physics is found to play important roles in the magnetotail dynamics, which leads to the following results: (1) There exists a systematic dawnward ion drift motion and thus a dawn-dusk asymmetry of the plasma sheet with a higher (lower) density on the dawn (dusk) side. Correspondingly, more reconnection occurs on the dusk side, and more high-speed earthward flow injections are found on the dusk side. (2) Earthward plasma injection due to the tail reconnection is investigated. The injected ions undergo the magnetic gradient and curvature drift in the dipole-like field, forming a ring current. (3) Ion particle distributions reveal multiple populations/beams at various distances in the tail. (4) Dipolarization of the tail magnetic field takes place at the fast flow braking, with oscillations predominantly on the dawn side. The dipolarization fronts are discussed. (5) Kinetic compressional wave turbulence is present around the depolarization, with kρi ~1. A shear-flow type instability is found on the dusk side flank of the ring current plasma, whereas a kinetic ballooning instability appears on the dawn side. (6) Shear Alfven waves and compressional waves are generated from the tail reconnection, and they evolve into kinetic Alfven waves (KAWs) in the dipole-like field region. Correspondingly, multiple field-aligned current filaments are generated above the auroral ionosphere.
