权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Collaborative Research (RUI): Understanding Potential Structures and Ion Dynamics Near Sheaths in Electronegative and Electropositive Multi-Species Bounded Plasma

合作研究 (RUI)：了解电负性和正电性多物种束缚等离子体中鞘层附近的电势结构和离子动力学

基本信息

批准号：
1804240
负责人：
Greg Severn
金额：
$ 27.23万
依托单位：
University of San Diego
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804240&HistoricalAwards=false
关键词：
Collaborative Research RUI Understanding Potential

项目摘要

The common states of matter on Earth are solids, liquids and gases. Putting energy into gases can result in the 4th state of matter known as plasma, which consists of electrically charged particles (electrons and ions, both positive and negative) and neutral atoms and molecules. While uncommon on the Earth, plasma makes up more than 99% of the visible matter in the universe. Where plasma comes in contact with material boundaries, a thin region near the plasma boundary usually forms to isolate the plasma from the boundary. This thin region is called the plasma sheath. Experiments to be performed under this award will improve our understanding of plasma sheaths and associated phenomena as fundamental to understanding all bounded plasmas. Plasmas studied in this work are similar to those used in plasma applications such as the etching of semiconducting materials to make computer chips, in plasma space propulsion satellite engines, and in experimental plasma fusion devices. The majority of experimental studies will be carried out at the University of San Diego (USD), which is primarily an undergraduate institution. The award will also support outreach activities to promote engagement of students with diverse backgrounds in science, technology, engineering and mathematics (STEM) disciplines.Experiments to be carried out at USD, in collaboration with University of Wisconsin - Madison, will address important questions associated with sheaths and the Bohm Criterion in multiple ion species plasma, both electropositive and electronegative, many for the first time. In previous work, this collaborative group discovered anomalous sheath edge velocities while testing the Bohm Criterion in two ion species plasma. This effect has now been theoretically explained via the introduction of ion-ion streaming instabilities. As a result, many different aspects of sheath formation must be reevaluated in light of the new theory. Moreover, there are as yet no such corresponding measurements for electronegative plasma with multiple ion species. This project will pursue experiments to perform such measurements, measurements that determine the presheath and sheath plasma potential profiles with emissive probes. Ion velocity distribution functions (IVDFs) associated with ion acceleration will be determined with tunable diode lasers using the laser-induced fluorescence (LIF) technique. The award will also support transfer of cutting edge research techniques to the classrooms and teaching laboratories for undergraduate and graduate students at the University of San Diego, and at the University of Wisconsin-Madison.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球上物质的常见状态是固体、液体和气体。将能量注入气体可以产生第四种状态的物质，即等离子体，它由带电粒子（电子和离子，正负都有）和中性原子和分子组成。虽然等离子体在地球上并不常见，但它占宇宙中可见物质的99%以上。当等离子体与物质边界接触时，通常在等离子体边界附近形成一个薄区域，将等离子体与物质边界隔离开来。这个薄的区域叫做等离子鞘。根据该奖项进行的实验将提高我们对等离子体鞘层和相关现象的理解，这是理解所有有界等离子体的基础。在这项工作中研究的等离子体类似于等离子体应用中使用的等离子体，例如用于制造计算机芯片的半导体材料的蚀刻，等离子体空间推进卫星发动机和实验等离子体聚变装置。大多数实验研究将在圣地亚哥大学（USD）进行，这是一个主要的本科机构。该奖项还将支持外展活动，以促进具有不同背景的学生在科学、技术、工程和数学（STEM）学科的参与。与威斯康星大学麦迪逊分校合作进行的实验将在多离子等离子体中解决与鞘和Bohm准则相关的重要问题，包括正电性和负电性，其中许多是首次。在之前的工作中，这个合作小组在测试两种离子等离子体的玻姆准则时发现了异常鞘层边缘速度。这种效应现在已经通过引入离子-离子流不稳定性在理论上得到了解释。因此，必须根据新理论重新评估鞘层形成的许多不同方面。此外，对于多离子的电负性等离子体，还没有相应的测量方法。该项目将继续进行实验来执行这些测量，测量用发射探针确定鞘前和鞘内等离子体电位分布。与离子加速相关的离子速度分布函数（IVDFs）将由可调谐二极管激光器使用激光诱导荧光（LIF）技术来确定。该奖项还将支持将尖端研究技术转移到圣地亚哥大学和威斯康星大学麦迪逊分校的本科生和研究生的教室和教学实验室。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。