Nonlinear Wave Experiments in Dusty Plasmas

该项目将利用国际空间站上一个名为Plasma Krystal-4（PK-4）的设施进行微重力实验，调查大振幅波的基本物理学。 波是运动的振荡，可以在许多物质中传播。在某些物质中，波很容易被看见，在某些物质中，波很容易被操纵，而在某些物质中，波的位移很大，因此它们呈现出一种不同的特性，称为非线性。在一种称为尘埃等离子体的物质中同时获得所有这三种特征是可能的，尘埃等离子体是浸入由电子、离子和中性分子组成的部分电离气体中的高电荷微米大小固体颗粒的混合物。 在该项目中，将使用视频显微镜观察大振幅波，并使用国际空间站上的实验仪器进行操纵。一名本科生将进行分析。该课题与其他研究领域有重叠，包括非线性动力学以及尘埃等离子体以外的其他等离子体物理领域。要分析的数据主要来自PK-4仪器，这是一个欧洲-俄罗斯仪器，现在在国际空间站上。返回地球的数据被分发给其他地方的科学家，包括爱荷华州大学。一台科学摄像机拍摄了一团聚合物微球的横截面，这些微球由于浸泡在弱电离等离子体中而带电。这种所谓的尘埃云维持着尘埃声波和电离条纹等波;这些波通过不稳定性自然增长，以获得非线性振幅。使用PK-4的数据是有价值的，因为在微重力条件下，尘埃云充满了比地球上的实验室实验更大的三维体积。为了支持这一努力，研究人员将与理论家合作描述非线性运动。 这项支持本科生的奖项是根据“美国宇航局/美国国家科学基金会关于尘埃等离子体科学的合作伙伴关系：利用国际空间站上的PK-4设施”颁发的，是对美国宇航局根据联合方案颁发的奖项的补充。

This project will utilize a facility called Plasma Krystal-4 (PK-4) on the International Space Station to conduct experiments in microgravity investigating the underlying physics of large amplitude waves. Waves are moving oscillations, which can propagate in many substances. In some substances waves are easily visible, in some they are easily manipulated, and in some the waves attain a large displacement so that they take on a different character called nonlinearity. Attaining all three of these characteristics at the same time is possible in a substance called a dusty plasma, which is a mixture of highly charged micron-size solid particles immersed in a partially ionized gas consisting of electrons, ions, and neutral molecules. In this project, large amplitude waves will be observed using video microscopy and manipulated using an experimental instrument on the International Space Station. An undergraduate student will carry out the analysis. The topic has an overlap with other fields of research including nonlinear dynamics as well as other plasma physics areas outside of dusty plasmas.The data to be analyzed are mainly from the PK-4 instrument, which is a European-Russian apparatus now on the International Space Station. Data returned to Earth are distributed to scientists at other locations including The University of Iowa. A scientific video camera images a cross-section of a cloud of polymer microspheres, which are electrically charged due to their immersion in a weakly ionized plasma. This so-called dust cloud sustains waves such as dust acoustic wave and ionization striations; these waves grow naturally, by an instability, to attain nonlinear amplitudes. The use of data from PK-4 is valuable because under microgravitiy conditions, the dust cloud fills a three-dimensional volume of greater size than is possible in laboratory experiments on Earth. To support this effort the investigators will collaborate with theorists in describing the nonlinear motion. This award to support an undergraduate student is made under a "NASA/NSF Partnership on Science of Dusty Plasmas: Utilizing the PK-4 Facility on board the International Space Station" and is complementary to a NASA award made under the joint program.