Dynamics of Strongly Coupled Complex Plasma Systems with Directed Ion Flow

这个研究项目将调查尾流，这是一种在自然界中广泛遇到的现象，跨越了一系列的长度尺度。在中子星星的弓形激波中观察到尾流，当空气流过海洋岛屿时，在云的图案中观察到尾流，在流动的溪流中在岩石后面观察到尾流。骑自行车的人利用他们的队友创造的尾流，骑在彼此后面以节省能量。 本研究探讨在复杂电浆中，带正电的离子流经带负电的尘埃粒子所形成的尾迹。复杂等离子体中的微米级尘埃粒子具有自组织成各种结构的能力。就像自行车手一样，被困在流动的等离子体中的尘埃粒子往往会在彼此的下游排成一行。 由于尘埃在韦克菲尔德中排列而节省的能量对尘埃结构的动力学和稳定性有影响。复杂等离子体是研究结构形成等动态效应的绝佳系统，因为它们允许在容易获得的空间和时间尺度上进行直接观察。研究复杂等离子体中的振荡模式和结构转变也可以深入了解其他有限系统的动力学，而这些有限系统不容易成像。许多尘埃等离子体实验利用悬浮在等离子体和边界表面之间形成的鞘层中的尘埃颗粒。 存在于鞘中的电场使等离子体离子朝向边界表面加速，从而导致颗粒下游的离子尾流。 本研究的主要目的是研究等离子体韦克菲尔德相互作用对复杂等离子体环境中自组装尘埃结构的自组织、动力学和相变的影响。这项研究融合了计算和实验技术。需要动态计算模拟，因为力、电荷和尾流都随着粒子位置和其他粒子的接近而变化。数值模型将提供离子流中尘埃粒子的动力学、充电和各向异性屏蔽的自洽计算。充电和韦克菲尔德的形成将与等离子体环境相联系，从而确定等离子体对边界条件的响应。与此同时，需要实验技术，可以以受控的方式产生特定的颗粒结构。实验室实验将采用最先进的技术，旨在控制和限制灰尘内的灰尘云，字符串，集群和晶体具有明确的特点。 在实验上，尘埃颗粒也将被用作原位探针，以测量当地的等离子体环境，为数字模型提供数据。

This research project will investigate wakes, a phenomenon widely encountered in nature and spanning a range of length scales. Wakes are observed in the bow shock of a neutron star speeding through interstellar gas, in cloud patterns as air flows past ocean islands, and behind rocks in flowing streams. Cyclists take advantage of the wake created by their teammates, riding close behind each other to conserve energy. This research investigates the wakes formed by positively charged ions flowing past negatively charged dust particles in a complex plasma. The micron-sized dust particles in a complex (dusty) plasma have the ability to self-organize into a wide variety of structures. Much like drafting cyclists, dust particles trapped in the flowing plasma tend to line up downstream of each other. The energy savings due to dust alignment in the wakefield has an effect on the dynamics and the stability of dust structures. Complex plasmas are an excellent system for studying dynamic effects such as structure formation, as they allow direct observation at easily accessible space and time scales. An investigation of the modes of oscillation and structural transitions in a complex plasma can also provide insight into the dynamics of other finite systems which cannot be easily imaged.Many dusty plasma experiments utilize dust grains suspended in the sheath formed between the plasma and a bounding surface. The electric fields present in the sheath accelerate the plasma ions towards the bounding surface, leading to an ion wake downstream of the grains. The primary objective of this research is to investigate the effect of the plasma wakefield interaction on the self-organization, dynamics, and phase transitions in self-assembled dust structures within a complex plasma environment. This research merges computational and experimental techniques. A dynamic computational simulation is needed, as forces, charges, and wakes all change with particle location and the proximity of other particles. Numerical models will provide self-consistent calculations of dynamics, charging and anisotropic screening of dust particles in an ion flow. Charging and wakefield formation will be linked to the plasma environment, defining the response of the plasma to boundary conditions. At the same time, experimental techniques are needed that can produce specific particle structures in a controlled manner. Laboratory experiments will employ state-of-the-art techniques designed to control and confine the dust within dust clouds, strings, clusters, and crystals with defined characteristics. Experimentally, dust particles will also be used as in situ probes to measure the local plasma environment providing data for use in the numerical models.