Dynamics of structure formation and self-organization in open systems

a .在无碰撞重连接的时间行为中有一个稳定的状态和一个间歇的状态，这取决于外部驱动流的空间轮廓。在小输入窗口尺寸的情况下，实现了稳态无碰撞重联，在上游边界重联速率与通量输入速率平衡，磁重联的全局动态过程主要由离子动力学控制，随着窗口尺寸的增大，电流片变长，有利于激发电子撕裂不稳定性。该系统演变成一个间歇性的制度，其中磁岛频繁地产生在电流片。在离子动力学和电子动力学的共同作用下，电流密度分布形成了双尺度结构。虽然整个重联系统的演化主要受外部条件的控制，但在二维稳态重联中，中性片处的电场更大，而与中心电子电流片中电子蜿蜒运动相关的电子压力张量是重联电场产生的主要原因。在三维情况下，等离子体的不稳定性被激发并影响无碰撞重联的动力学行为。在外部驱动源存在的情况下，外围激发的较低混合漂移波向中性片传播，从而在电流片中产生异常电阻率。因此，外部驱动电场渗透到电流片中并触发中性点片的磁重联。磁岛是由于磁重联在下游产生的，但它们在扭结不稳定的情况下变得不稳定。磁岛通过下游边界消失后，系统暂时松弛到准稳态。具有与离子旋转频率相当的低频电磁模式（漂移-扭结不稳定性）在电流片中缓慢生长并改变了空间结构。通过二维和三维电磁粒子模拟，研究了空心电流剖面的自生过程及其对反场构型倾斜不稳定性的影响。系统自发地从磁流体动力学平衡松弛到动力学平衡，在动力学平衡中，电子电流分布变得空心。在空心电流型和高分离矩阵β值的情况下，倾斜不稳定性的增长率小于峰值电流型。当磁分离矩阵形状较长时，不稳定区定位在边缘附近，对倾斜不稳定起稳定作用。少

A. There are a steady regime and an intermittent regime in the temporal behavior of collisionless reconnection, dependently on the spatial profile of an external driving flow. The steady collisionless reconnection is realized in the case of small input window size, in which the reconnection rate is balanced with the flux input rate at the upstream boundary and the global dynamic process of magnetic reconnection is dominantly controlled by ion dynamics : As the window size increases, the current sheet becomes longer, which is favorable to the excitation of an electron tearing instability. The system evolves into an intermittent regime, in which magnetic islands are frequently generated in the current sheet. Two-scale structure is formed in the current density profile through combined actions of both ion and electron dynamics. Electron pressure tensor associated with electron meandering motion in the central electron current sheet is a main cause of generation of reconnection electric fi … More eld at neutral sheet in two-dimensional steady reconnection, although the evolution of the whole reconnection system is controlled mainly by an external condition.B. In three-dimensional case plasma instabilities are excited and affect the dynamical behavior of collisionless reconnection. In the presence of an external driving source the lower hybrid drift waves excited in the periphery propagate toward the neutral sheet and thus generate anomalous resistivity in the current sheet. Consequently, the external driving electric field penetrates into the current sheet and triggers magnetic reconnection at the neutral sheet. Magnetic islands are created in the downstream as a result of magnetic reconnection, but they become unstable against the kink instability. After magnetic islands disappear through the downstream boundary, the system relaxes into a quasi-steady state temporarily. An electromagnetic (EM) mode with a low-frequency comparable to ion gyration frequency (drift-kink instability) grows slowly in the current sheet and modifies the spatial structure.C. Self-generation process of hollow current profile and its influence on tilting instability in field-reversed configurations are investigated by means of two-dimensional and three-dimensional EM particle simulations. The system spontaneously relaxes from a magnetohydrodynamic equilibrium toward a kinetic one, in which the electron current profile becomes hollow. Growth rate of the tilting instability in the case of the hollow current profile and high separatrix beta value is smaller than that in the case of the peaked current profile. When magnetic separatrix shape is much prolate, the unstable region is localized near the edges, and stabilization of the tilt instability becomes effective. Less