SPRG Seminars
March 15, 2011:
"3-D Global Hybrid Simulation of Plasma Processes in the Bow Shock and Dayside"
Yu Lin, Auburn University
Hybrid simulation model is a self-consistent kinetic model that treats ions as fully kinetic particles and electrons as a massless fluid. It can be utilized for kinetic physics corresponding to wave frequency w ~ W i and wave number k r i ~1, where W i and r i are ion gyrofrequency and ion Larmor radius, respectively. Using a 3-D global hybrid code, we have carried out simulations of various plasma processes at the Earth's bow shock and dayside magnetopause. In this talk, the following simulation results will be discussed. (1) In the cases in which the direction of interplanetary magnetic field (IMF) is such that the bow shock is a quasi-parallel shock , t he interaction of foreshock waves/ pressure pulses with the dayside magnetosphere leads to strong surface perturbations at the magnetopause. Meanwhile, the compressional waves are found to mode convert to shear Alfven waves and kinetic Alfven waves (KAWs) through the Alfven resonance process at the magnetopause , which in turn produces field line resonance and field-aligned currents in the magnetosphere. (2) Furthermore, the global signatures of ion acceleration near the quasi-parallel bow shock are examined and compared with satellite observation s . The linkage between the cusp energetic ions (CEPs) and the foreshock diffuse ions is discussed. (3) Finally, for cases with a southward IMF, the structure and evolution of magnetic reconnection at the magnetopause are investigated . In particular, energy spectra of cusp precipitating ions associated with the magnetopause reconnection shows a dispersive feature consistent with satellite observations. By tracing trajectories of the transmitted magnetosheath ions, the origin of the dispersive ion spectrum is revealed.