Experimental Investigation of Spontaneous Double Layers in Expanding Plasmas

膨胀等离子体中自发双层的实验研究

• 批准号: 1360278
• 负责人: EARL SCIME
• 金额: $ 59万
• 依托单位: West Virginia University Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1360278&HistoricalAwards=false
• 关键词: Experimental; Investigation; Spontaneous; Double; Layers

Over the last decade, plasma researchers have observed the surprising result that when a plasma expands along a weakening magnetic field, beams of high speed ions shooting out along the magnetic field spontaneously appear. Expanding plasmas are common in nature, such as the atmosphere of the Sun, and in 21st century technology, such as in some rocket engines and industrial systems. This project explores the stability and the detailed structure of the ion acceleration process in hopes of developing a better understanding of the most important processes responsible for the ion acceleration.The group will measure the stability thresholds for spontaneously forming double layers (sheaths) in expanding single and multiple ion species plasmas; the effects of neutral density in the double layer region on double layer structure and stability; and the spatial structure and plasma parameter dependence of the electric fields in the expansion region that result in the formation of multiple ion beams. Integrated with these investigations is the application of new diagnostic tools for the measurement of densities and flows of ions and neutrals in low temperature plasmas. The formation and stability of double layers in single-ion and multi-ion plasmas is a fundamental plasma physics question with important ramifications for systems ranging from space plasmas to plasma thrusters. Beyond the scientific contributions that this research will make to our understanding of double layer formation and stability, the broader impact of the work involves the training of graduate students in a research environment that emphasizes the synergy between basic and applied plasma physics; improvement of the percentage of women and minorities obtaining advanced degrees in physics; attracting high quality undergraduates into physics through involvement in cutting-edge research activities; and support of a STEM education initiative that extends to over half the counties in West Virginia and that is continuing to expand.

在过去的十年中，等离子体研究人员观察到令人惊讶的结果，即当等离子体沿着磁场较弱的磁场膨胀时，高速离子的光束沿磁场沿磁场发射出来。扩展的等离子体在本质上很常见，例如太阳的气氛和21世纪的技术，例如在某些火箭发动机和工业系统中。该项目探讨了离子加速过程的稳定性和详细结构，以期使对负责离子加速的最重要过程有更好的了解。该小组将在扩展单个和多个离子物种等离子体中衡量自发形成双层（鞘）的稳定性阈值；双层区域中中性密度对双层结构和稳定性的影响；以及在扩展区域中电场的空间结构和等离子体参数依赖性，从而导致多个离子束的形成。与这些研究集成在一起的是将新诊断工具应用于低温等离子体中离子和中性的密度和流量的测量。双离子和多离子等离子中双层的形成和稳定性是一个基本的等离子体物理问题，具有重要的影响，从空间等离子体到等离子体推进器的系统。除了这项研究对我们对双层形成和稳定性的理解所做的科学贡献之外，这项工作的更广泛影响还涉及在研究环境中培训研究生，该研究环境强调了基本的血浆物理学和应用血浆物理学之间的协同作用；提高妇女和少数族裔的百分比，获得了物理学的高级学位；通过参与尖端研究活动，吸引高质量的本科生进入物理学；并支持一项STEM教育计划，该计划扩展到西弗吉尼亚州的一半以上，并且正在继续扩大。