Simulation Study of Space Plasma Physics

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The advent of systematic studies of space plasmas by large- scale and sophisticated computer simulations has brought in an exciting era to S/T research and has become an important component of the discipline. This grant will support a numerical study closely corroborated with analytical theory and observations. It will continue research on the generic problems of driven reconnection, current interruption, and magnetic energy release and their manifestations in magnetospheric and solar plasmas. This work is based on the following hypotheses: (i) Energetic substorms are primarily a process characterized not by a spontaneous tearing process, but by driven linear and nonlinear instabilities. Solar flares are the source of magnetic wind disturbances, which induce the Kelvin-Helmholtz instability in the magnetopause and in turn trigger substorms; (ii) The onset of coronal flares is quite rapid and violent and is often a process (once again) driven by adjacent current carrying coronal loops or photospheric mechanical motion; (iii) this mechanical motion is a manifestation of a more global motion of flux loops or matter beneath the photosphere through magnetic buoyancy and convective instabilities. One example of such coupling: the twisting of current ropes beneath the photosphere causes buoyancy of the ropes and conversely the emergence of loops in sheared magnetic fields gives rise to twisted loops. It is intended to piece together the dynamic interplay of these physical processes using insights obtained from simulation studies. The overall aim is to understand the basic plasma physical processes at the sun and their impact at the earth.