Complex plasmas are interesting systems as the charged dust can self-assemble into different types of ordered structures. To understand the mechanisms which govern the transitions from one type of structure to another, it is necessary to know both the dust charge and the confining electric fields within the environment, parameters which are difficult to measure independently. As dust is usually confined in a plasma sheath where the ions stream from the bulk plasma to the negative lower electrode, the problem is further complicated by the ion wake field, which develops downstream of the dust grains in a flowing plasma. The differences in local ion density caused by the wake field change the equilibrium dust charge and shielding distance of the dust grains, and thus affect the interaction between grains. Here we use a molecular dynamics simulation of ion flow past dust grains to investigate the interaction between the dust particles and ions. We consider a long vertical chain of particles confined within a glass box placed on the lower electrode of a Gaseous Electronics Conference rf reference cell. We apply the model iteratively to self-consistently determine the dust charge, electric field, and ion density along the length of the chain as well as the ion flow speed. Simulation results indicate that the ion flow speed within the box is subsonic.

中文翻译：

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灰尘作为探针：确定约束力和相互作用力

复杂的等离子体是有趣的系统，因为带电的灰尘可以自组装成不同类型的有序结构。为了理解控制从一种类型的结构过渡到另一种类型的结构的机制，有必要了解环境中的粉尘电荷和约束电场，这些参数很难独立测量。由于灰尘通常被限制在等离子体鞘中，在离子鞘中离子从体等离子体流向负下电极，因此离子流场使问题进一步复杂化，该离子流场在流动的等离子体中在尘埃颗粒的下游产生。由尾流场引起的局部离子密度的差异改变了粉尘颗粒的平衡粉尘电荷和屏蔽距离，从而影响了粉粒之间的相互作用。在此，我们使用离子流经过尘埃颗粒的分子动力学模拟来研究尘埃颗粒与离子之间的相互作用。我们考虑了一个颗粒的垂直长链，该颗粒被限制在玻璃盒中，该玻璃盒放置在气体电子会议射频参考电池的下部电极上。我们迭代地应用该模型，以自洽地确定沿着链的长度的粉尘电荷，电场和离子密度以及离子流速。仿真结果表明，盒子内的离子流速是亚音速的。我们迭代地应用该模型，以自洽地确定沿着链的长度的粉尘电荷，电场和离子密度以及离子流速。仿真结果表明，盒子内的离子流速是亚音速的。我们迭代地应用该模型，以自洽地确定沿着链的长度的粉尘电荷，电场和离子密度以及离子流速。仿真结果表明，盒子内的离子流速是亚音速的。