Study of Solar Radio Emission Mechanisms

太阳射电发射机制研究

• 批准号: 0341084
• 负责人: Peter Yoon
• 金额: $ 25.59万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0341084&HistoricalAwards=false
• 关键词: Study; Solar; Radio; Emission; Mechanisms

The investigators will develop a quantitative theoretical and numerical analysis of electromagnetic plasma weak turbulence, with the aim of investigating the basic radiation mechanism at the plasma frequency and its harmonics. Such a mechanism, known in the literature as the plasma emission, is accepted as the process responsible for solar type II and type III radio bursts in the corona and interplanetary space. Despite more than 40 years of theoretical research on this topic, however, the basic set of equations have not been quantitatively solved to this date, owing to the enormous complexity associated with obtaining such a solution. In this research program, the basic theory of plasma emission will be reformulated from the most basic set of equations governing the plasma dynamics. Once the electromagnetic effects are fully taken into account, the numerical code will be developed to solve the final set of equations. However, unlike the Langmuir turbulence problem where a one-dimensional approximation reasonably describes the essential physics, the electromagnetic plasma emission problem requires at least a two-dimensional treatment at the outset. The final numerical result is expected to lead to a much better understanding of the plasma emission problem, and help resolve some of the outstanding issues such as the wave growth period, the saturated spectrum, and most importantly, the issue associated with the relative efficiency of the standard three-wave process versus an alternative mechanism which involves the excitation of the so-called nonlinear beam mode. The study may have impacts on other fields, e.g., laser-plasma interaction, microwave generation devices, beam-plasma discharge, rocket active experiments, ionospheric microwave heating experiments, solar and interplanetary radio wave bursts and energetic particles, bow-shock radio waves and energetic particles, and cosmic rays.

研究人员将对电磁等离子体弱湍流进行定量的理论和数值分析，目的是研究等离子体频率及其谐波的基本辐射机制。这种机制在文献中被称为等离子体发射，被认为是导致日冕和行星际空间中的第二类和第三类射电爆发的过程。然而，尽管对这一主题进行了40多年的理论研究，但由于获得这种解的巨大复杂性，基本的一组方程至今还没有得到定量的解。在这个研究计划中，等离子体发射的基本理论将从控制等离子体动力学的最基本的一组方程中重新表述出来。一旦充分考虑了电磁效应，将开发数值代码来求解最终的方程组。然而，与朗缪尔湍流问题不同，在朗缪尔湍流问题中，一维近似合理地描述了基本物理，而电磁等离子体发射问题在一开始就需要至少进行二维处理。最终的数值结果将有助于更好地理解等离子体发射问题，并有助于解决一些悬而未决的问题，如波的增长周期、饱和频谱，以及最重要的与标准三波过程与涉及激发所谓的非线性束流模式的替代机制的相对效率相关的问题。这项研究可能会对其他领域产生影响，例如激光-等离子体相互作用、微波产生装置、束-等离子体放电、火箭活动实验、电离层微波加热实验、太阳和行星际无线电波爆发和高能粒子、弓激波无线电波和高能粒子，以及宇宙射线。