标题： 射电辐射在湍流日冕等离子体中的线性模式转换理论 显示英文标题

标题： Linear mode conversion theory of radio emission from turbulent solar wind plasmas

摘要： 本工作提出了一种新的理论和数值模型，描述太阳风等离子体中所有可能的上混合波湍流与随机密度涨落之间的线性相互作用；不仅考虑了波反射、折射、散射、隧穿、俘获或恒频下的模态转换等线性过程，还考虑了线性波耦合、散射波之间的干涉等现象。 描述由于上混合波在密度涨落上的变换所产生的电流辐射的$\mathcal{O}$、$\mathcal{X}$和$\mathcal{Z}$模式中的电磁场随时间演化的紧凑方程，以及这些模态的色散和偏振特性，通过解析方法确定并数值求解，提供了电磁能量及其相应辐射率的时间变化。 结合这些验证理论假设的数值结果，在扩展到随机非均匀等离子体的弱湍流理论框架内进行解析计算，恢复了使用新模型所陈述的主要物理结论。 辐射率对等离子体参数如磁化程度、电子热速度和随机密度涨落的平均水平的依赖关系以尺度定律的形式确定。 本工作为分析太阳风等离子体中真实波和密度湍流谱相互作用时等离子体频率处电磁辐射的效率提供了一种新方法。 显示英文摘要

摘要： This work presents a new theoretical and numerical model describing all possible linear interactions between upper-hybrid wave turbulence and random density fluctuations in a solar wind plasma; not only linear processes as wave reflection, refraction, scattering, tunneling, trapping, or mode conversion at constant frequency are taken into account, but also linear wave coupling, interferences between scattered waves, etc. Compact equations describing the time evolution of electromagnetic fields radiated in the $\mathcal{O}$, $\mathcal{X}$ and $\mathcal{Z}$ modes by the current due to transformations of upper-hybrid waves on density fluctuations, as well as the dispersion and polarization properties of the modes, are determined analytically and solved numerically, providing the time variations of electromagnetic energies and corresponding radiation rates. Jointly, on the basis of these numerical results that validate theoretical hypotheses, analytical calculations are conducted in the framework of weak turbulence theory extended to randomly inhomogeneous plasmas, that recover the main physical conclusions stated using the new model. The dependencies of radiation rates on plasma parameters as the magnetization, the electron thermal velocity and the average level of random density fluctuations are determined in the form of scaling laws. This work opens a new way to analyze the efficiency of electromagnetic emissions at plasma frequency by realistic wave and density turbulence spectra interacting in solar wind plasmas.