Study of Solar Radio Emission Mechanisms

研究人员将对电磁等离子体弱湍流进行定量理论和数值分析，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，在文献中称为等离子体发射，被认为是日冕和行星际空间中太阳II型和III型射电爆发的原因。 然而，尽管对这一主题进行了40多年的理论研究，但由于与获得这种解决方案相关的巨大复杂性，基本方程组至今尚未定量求解。 在本研究计划中，等离子体发射的基本理论将从最基本的等离子体动力学方程组重新制定。 一旦电磁效应被充分考虑，数值代码将被开发来解决最终的方程组。 然而，不像朗缪尔湍流问题，其中一维近似合理地描述了基本的物理，电磁等离子体发射问题需要至少在一开始的二维处理。 最终的数值结果预计将导致更好地理解等离子体发射问题，并帮助解决一些悬而未决的问题，如波的生长周期，饱和光谱，最重要的是，与标准的三波过程相对于替代机制，其中涉及所谓的非线性束模式的激发的相对效率的问题。 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、微波发生装置、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、弓形激波无线电波和高能粒子以及宇宙射线。

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.