Collaborative Research: Fundamental Charging Processes of Dust in Complex Plasmas

复杂等离子体，也被称为尘埃等离子体，由离子、电子和带电尘埃组成，这些微小的固体颗粒比人类头发的宽度小得多。尘埃等离子体长期以来一直是天体物理学界的兴趣所在，因为在大多数太空环境中都发现了尘埃和电离气体，包括恒星和行星形成的云、彗星尾巴、行星环和地球电离层中的夜光云。尘埃等离子体在应用环境中也存在于地球上。它们是在工业等离子体处理设备中使用的化学活性气体中形成的，用于制造计算机芯片，污染最终产品并降低总体产量。核聚变装置内的粉尘污染也是一个问题，因为通过侵蚀安全壳壁产生的粉尘会引起安全（操作不稳定）和健康（长期污染）问题。实验室等离子体中尘埃晶体、团簇和弦的形成也被证明是原子和分子系统的有力模拟。尘埃颗粒的带电是尘埃等离子体的一个独特而重要的方面。事实证明，了解这种带电和随后在等离子体中形成的尘埃结构背后的物理原理需要细致入微的细节。尘埃颗粒获得的电荷是由等离子体环境决定的，而带电粒子反过来又影响等离子体环境。电荷的局部变化，无论是在单个粉尘颗粒的表面还是组成较大结构的多个粉尘颗粒的表面，都可以影响颗粒的局部动力学和整个系统的演化。许多情况将不对称引入到这个问题中，使得电荷难以解析描述。复杂的因素包括空间的变化（由于尘埃结构的几何形状或等离子体环境）以及时间的变化（由于等离子体对移动尘埃颗粒或随机充电过程的响应）。粉尘电荷量在实验中也极难确定。因此，本研究的主要目的是确定电荷在时间和空间上的变化如何影响和响应等离子体环境中尘埃粒子的动力学和结构。为了实现这一目标，数值模拟技术将与实验室实验相结合，以提供对控制系统行为的过程的正确理解。数值模型将用于模拟尘埃结构上的时间和空间电荷变化，包括随机效应，以解决由于等离子体粒子的离散性而导致的时间变化。充电还将与等离子体环境的数值模型联系起来，该模型定义了等离子体对边界条件和尘埃本身的响应。同时，实验室实验将采用最先进的技术来控制和限制尘埃在尘埃云，弦，簇和聚集体中，以便将它们用作原位探针来测量局部等离子体环境。

Complex plasmas, also known as dusty plasmas, consist of ions, electrons and charged dust, tiny solid particles much smaller than the width of a human hair. Dusty plasmas have long been of interest in the astrophysics community, due to the fact that dust and ionized gas are found in most space environments, including the clouds from which stars and planets form, comet tails, planetary rings, and noctilucent clouds in the earth's ionosphere. Dusty plasmas are also present on Earth in applied settings. They are formed in the chemically active gases used in industrial plasma processing devices to create computer chips, contaminating the end product and reducing overall yield. Dust contamination within fusion devices is also an issue, since dust produced through erosion of the containment walls raises both safety (operating instabilities) and health (long-term contamination) concerns. The formation of dust crystals, clusters and strings in laboratory plasmas has also proven to be a capable analog for atomic and molecular systems. Charging of dust grains is a unique and important aspect of dusty plasmas. Understanding the physics behind this charging and subsequent formation of dust structures immersed within plasma has proven to require nuanced details. The charge acquired by the dust grains is determined by the plasma environment, but the charged particles in turn influence this environment. Local variations in the charge, either over the surface of a single dust grain or the multiple dust grains comprising a larger structure, can affect both the grain's local dynamics and the evolution of the overall system. Many situations introduce asymmetries into this problem, making the charge difficult to describe analytically. Complicating factors include variations in space (due to geometry of the dust structure or of the plasma environment) as well as variations in time (due to the response of the plasma to the moving dust grains or stochastic charging processes). The dust charge is also extremely difficult to determine in experiments. Thus, the primary objective of this research is to determine how variations in charge in both time and space influence and respond to the dynamics and configuration of dust particles in plasma environments.In order to accomplish this goal, numerical modeling techniques will be combined with laboratory experiments to provide a proper understanding of the processes governing the system behavior. Numerical models will be used to model temporal and spatial charge variation over the dust structures, including stochastic effects to resolve the variations in time due to the discrete nature of the plasma particles. The charging will also be linked to numerical models of the plasma environment which define the response of the plasma to boundary conditions and the dust itself. Simultaneously, laboratory experiments will employ state-of-the-art techniques to control and confine the dust within dust clouds, strings, clusters, and aggregates in order to use them as in situ probes to measure the local plasma environment.