Effect of ion flows on heating and instabilities in weakly coupled dusty plasmas

离子流对弱耦合尘埃等离子体中的加热和不稳定性的影响

• 批准号: 0810419
• 负责人: Edward Thomas
• 金额: $ 42.6万
• 依托单位: Auburn University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810419&HistoricalAwards=false
• 关键词: Effect; ion; flows; heating; instabilities

Dusty (complex) plasmas are four-component plasma systems that consist of ions, electrons, neutral particles, and the addition of a fourth species, charged microscopic particles or "dust". The charged dust, which is typically composed of micron- or nanometer-sized particles, fully interacts and self-consistently modifies the properties of the surrounding plasma. Once primarily focused on astrophysical phenomena such as planetary rings or interstellar dust, the growth of laboratory studies of the role of charged microparticles in plasmas has offered a unique opportunity to observe plasma physics phenomena at the kinetic level. As a result, this field has become, over the last two decades, a robust scientific enterprise within the larger field of plasma science.In laboratory studies, the microparticles become charged through the collection of ions and electrons from the background plasma. This process alters the ion and electron distributions in the plasma. Furthermore, in the presence of flows in the plasma, particularly ion flows, not only are the charging conditions of the microparticles modified, but the flows alter the force balance that allows the microparticles to remain suspended in the plasma and provide a free energy source for heating the microparticles and driving instabilities. Thus, a continuing challenge to the understanding of dusty plasmas remains the interaction between the charged microparticles and the ions. However, a complete model of this ion drag force remainselusive and an essential piece of information for resolving the differences among the models "the ion drift velocity" is often difficult to obtain in many experiments.Most studies of ion-dust interactions infer the ion flow either from collected currents on probes or by the response of the dust particles to an applied perturbation. In this investigation, the PI proposes to directly and independently measure both the ion flow and the dust response to determine the correlation between these two parameters. To accomplish this, the PI?s group will utilize its unique capabilities for optical measurements of microparticle velocities using two-dimensional and stereoscopic particle imaging velocimetry (PIV). PIV facilitates measurements of microparticle transport and the velocityspace distribution function of the microparticle component of the plasma. Furthermore, through a collaboration with Prof. Earl Scime's group at West Virginia University and access to the Auburn Fusion Laboratory's dye laser system, the PI proposes to use laser induced fluorescence (LIF) to directlymeasure ion flow velocities in the plasma. Additionally, complementary studies using Prof. Robert Merlino's Dusty Plasma Device at the University of Iowa will allow a verification of the measurements performed at the PI's laboratory at Auburn University.Consequently, this proposed work offers a unique opportunity to address a number of outstanding questions of importance to the dusty plasma community. Specifically, this project will investigate two specific aspects of ion-dust interactions: (a) testing a proposed model of dusty plasma heating thatoccurs via an ion-dust two-stream instability; and (b) characterizing how ion flow acts as a trigger for the generation of dust acoustic waves.This proposed research project has several opportunities to have a broader impact. The PI will continue to actively engage undergraduate and graduate students and post-doctoral scholars in hands-on research training. The PI has a successful track-record of student training and will continue encourageand include student participation in publications, national and international conferences, and laboratory outreach activities. Additionally, this work will support collaborative activities among different researchers within the dusty plasma community (e.g., at Auburn and Iowa) and establish a newpartnership (with WVU), thereby strengthening the community of researchers involved in basic plasma science. Furthermore, this project will provide continuing support for many of the public outreach activities that have been undertaken by the PI's laboratory to illuminate the physics of plasmas and dusty plasmas.Funds for this award are provided by the Physics Division and the Office of Multi-disciplinary Activities within the NSF's Mathematics and Physical Sciences Directorate, Combustion, Fire, and Plasma Systems within NSF's Engineering Directorate, and the Office of Fusion Energy Sciences of the DoE within the context of the NSF/DOE Partnership in Basic Plasma Science and Engineering.

尘土飞扬（复杂）等离子体是四组分等离子体系统，由离子，电子，中性颗粒和添加第四种，带电的显微镜颗粒或“灰尘”组成。带电的灰尘通常由微米或纳米尺寸的颗粒组成，完全相互作用并自愿修改周围血浆的特性。一旦主要集中在天体物理现象（例如行星环或星际尘埃）上，实验室研究的实验室研究为电荷微粒在等离子体中的作用提供了独特的机会，可以在动力学水平上观察血浆物理现象。结果，在过去的二十年中，该领域已成为更大的等离子科学领域的强大科学企业。在实验室研究中，微粒通过从背景等离子体的离子和电子收集来收取。这个过程改变了等离子体中的离子和电子分布。此外，在血浆中存在流，尤其是离子流中的情况下，不仅修改了微粒的充电条件，而且流动会改变力平衡，这使得微粒可以保持在等离子体中的悬浮，并提供了加热微粒颗粒和驱动不便的自由能源。因此，对灰尘等离子体的理解的持续挑战仍然是带电的微粒与离子之间的相互作用。但是，在许多实验中，通常很难获得该离子阻力的完整模型，并且是解决“离子漂移速度”之间差异的必不可少的信息。对离子偶相互作用的大多数研究推断了从探针上收集的电流或通过探针响应粉尘粒子对施加扰动的响应来推断离子流的研究。在这项研究中，PI提议直接和独立地测量离子流和尘埃响应，以确定这两个参数之间的相关性。为此，使用二维和立体粒子成像速度法（PIV），PI组将利用其独特的功能来对微粒速度进行光学测量。 PIV促进了血浆中微粒分量的微粒传输和速度空间分布函数。此外，通过与西弗吉尼亚大学Earl Scime教授的小组合作，并使用Auburn Fusion Laboratory的染料激光系统，PI建议使用激光诱导的荧光（LIF）来直接衡量等质量的离子流速度。此外，在爱荷华大学使用罗伯特·梅里诺（Robert Merlino）的尘土飞扬的血浆设备进行互补研究将允许验证奥本大学（Auburn University）在PI的实验室进行的测量结果。此后，这项提议的工作提供了一个独特的机会，可以解决一些对尘土等离子体社区的重要问题。具体而言，该项目将研究离子盘相互作用的两个特定方面：（a）通过离子旋转的两际流不稳定性测试提出的尘土等离子体加热的模型； （b）表征离子流程如何成为产生尘埃波的触发因素。该提出的研究项目有几个机会产生更大的影响。 PI将继续积极参与本科生和研究生以及博士后学者的动手研究培训。 PI拥有成功的学生培训赛道，并将继续鼓励学生参加出版物，国家和国际会议以及实验室外展活动。此外，这项工作将支持Dusty等离子体社区（例如在奥本和爱荷华州）中不同研究人员之间的合作活动，并建立了Newpartnershers（与WVU），从而加强了参与基本等离子体科学的研究人员社区。此外，该项目将为PI实验室进行的许多公共外展活动提供持续的支持，以阐明该奖项的等离子体和尘土飞扬的物理。在基本等离子体科学与工程领域的NSF/DOE合作伙伴关系的背景下，DOE的融合能源科学。