Localized particle-like excitations in a gas discharge system and their dynamics

被驱使失去平衡的系统往往表现出宏观结构从最初的无特征状态自发地组织起来；这些结构存在于自然界中各种物理、化学和生物系统中，它们要么是全局分布的，要么是高度局域化的、类似粒子的。由于这样的宏观结构通常是由系统持续的能量和/或材料供应及其耗散之间的平衡来维持的，普里戈金将其命名为“耗散结构”，以区别于微观的“平衡结构”，如晶体。虽然耗散结构与平衡结构有一些相同的特征，但前者与后者有很大的不同，因为前者能够表现出在后者中从未观察到的各种动力学行为。事实上，许多非平衡系统在One和…中表现出全球分布的耗散结构的复杂演化更多的两个空间维度及其动力学已被广泛研究。在许多系统中也观察到了一维局域耗散结构的复杂动力学。但二维局域耗散结构的例子很少，对它们的行为也知之甚少。我们发现，在直流驱动的准二维气体放电系统中，高度局域的、动态的类粒子激发是自组织的。这些局域激发(点)即使在单个光点存在的情况下也表现出非常不规则的运动，当存在多个光点时，根据控制参数值的不同，形成孤立或聚集的状态。在聚集态，它们形成一个漂移的分子状簇合物，其内部结构通过重新排列元素的相互位置而间歇性地变化。这些局域激发即使在遥远的地方也能表现出同步动力学的事实，结合最近的理论研究，表明全局耦合在这种局域激发的动力学中起着重要的作用。较少

Systems driven out of equilibrium often show spontaneous organization of macroscopic structures from an initial featureless state ; these structures are found in diverse physical, chemical and biological systems in nature, and they are either globally distributed throughout the system or highly localized and particle like. Because such macroscopic structures are, in general, maintained by the balance between continuous supply of energy and/or materials to the system and its dissipation, Prigogine named them as 'dissipative structures' to distinguish it from microscopic 'equilibrium structures' such as crystals. Although dissipative structures share some features with equilibrium structures, the former is quite different from the latter in the point that the former is capable of showing a variety of dynamic behaviors that are never observed in the latter. Indeed, many nonequilibrium systems are known to exhibit complex evolution of globally distributed dissipative structures in one and … More two spatial dimensions and their dynamics has been extensively studied. Complex dynamics of one-dimensional localized dissipative structures has also been observed in many systems. But few examples are known for two-dimensional localized dissipative structures, and little is known about their behaviors.We find that highly localized, dynamic particle-like excitations are self-organized in a d.c.-driven, quasi two-dimensional gas-discharge system. These localized excitations (spots) exhibits quite irregular motion even when a single spot is present, and form either isolated or aggregated state when more than one spot is present, depending on the control parameter values. In aggregated state, they form a wandering molecule-like cluster, whose internal structure changes intermittently by rearranging mutual position of elements. The fact that these localized excitations can show synchronous dynamics even in distant places, together with recent theoretical studies, indicates that a global coupling plays an important role on the dynamics of such localized excitations. Less