Simulation Study of Space Plasma Physics

大规模、精密的计算机模拟系统研究空间等离子体的出现，使S/T研究进入了一个激动人心的时代，并成为该学科的一个重要组成部分。这笔拨款将支持一项与分析理论和观察密切相关的数值研究。继续研究磁层和太阳等离子体中驱动重联、电流中断和磁能释放的一般性问题及其表现。这项工作基于以下假设：(i)高能亚暴主要是一个过程，其特征不是自发撕裂过程，而是驱动的线性和非线性不稳定性。太阳耀斑是磁风扰动的来源，磁风扰动诱发磁层顶的开尔文-亥姆霍兹不稳定性，进而引发亚暴；（ii）日冕耀斑的爆发相当迅速和猛烈，并且常常是（再次）由携带日冕环或光球机械运动的邻近电流驱动的过程；（iii）这种机械运动是光球下通量环或物质通过磁浮力和对流不稳定性进行更全面运动的一种表现。这种耦合的一个例子是：光球下的电流绳索的扭曲导致绳索的浮力，相反，在剪切磁场中出现的环产生了扭曲的环。它的目的是利用从模拟研究中获得的见解来拼凑这些物理过程的动态相互作用。总体目标是了解太阳的基本等离子体物理过程及其对地球的影响。

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.