电离层人工改性回旋加热机理与影响研究

Nonlinear phenomena near electron gyroharmonic heating will be investigated to explore the mechanism for producing artificial ionospheric layer. Artificial ionospheric layer has been observed at the most powerful 3.6MW high frequency heating facility HAARP. Such strongly ionospheric modification has been optimized with narrowband frequency pumping near electron gyroharmonic and beam shaping. This phenomenon is associated with superthermal electrons, which cause ionization of neutral gases in the ionosphere. HF pump induced plasma turbulence near resonance regions can lead to stimulated electromagnetic emissions SEEs, which can directly provide diagnostics of the ionosphere. Nonlinear evolution of SEE excitation and related phenomena will be investigated using a kinetic model. Impacts of plasma disturbance will be studied based on incoherent scatter theory, including plasma and ion line enhancement. Also, the coherent radar backscatter from plasma irregularities will be considered as well. This project aims to study the generation and its impact of artificial plasma disturbance by high power radio waves self-consistently.

采用地面大功率高频电磁波设备HAARP对电离层进行人工改性，产生新的等离子体层（Artificial Ionospheric layer），可改善高频通信质量。人工等离子体层，采用电子回旋频率多次谐波的加热方式，产生能量超过中性气体电离阈值的超热电子。超热电子的加速机制，与回旋加热和非线性共振作用密切相关。在电离层回旋共振高度，电磁波通过参量不稳定性激发次级电磁发射，可直接用来诊断电子加速机制。采用多维动力学模型，研究电子回旋加热共振机制中的非线性物理过程。阐述参量不稳定性产生波恩斯坦坦波/高频混杂波对电子的加热机理。同时，研究电离层人工改性产生的非线性现象对电磁波传播和散射产生的影响。本课题形成研究电离层小尺度扰动产生机理及其影响的系统和理论，为人工电离层改性实验提供参考。

本课题研究电离层磁回旋加热过程的基本问题电子加速机制，研究电磁波和等离子体的非线性作用机制，小尺度等离子体不规则体的激发机理及效应。 首先, 采用多维动力学模型，首次建立的电离层加热受激四波参量不稳定性理论和二维动力学仿真模型，得到了受激电磁辐射拓展上行谱的主要特征及激发阈值，研究了小尺度等离子体不规则体的非线性发展过程, 揭示了高频混杂波/电子伯恩斯坦波对电子的加热机制，找到了实现电离层加热电子的最优参数。其次，将电流密度卷积时域有限差分方法扩展到求解任意磁偏角电磁波在非均匀磁化电离层等离子体中的传播和共振吸收问题。研究不同极化和入射角度情况下,电磁波在磁化等离子体中三种共振机制:电子回旋共振，等离子体朗缪尔共振和高频混杂共振吸收机制。结果表明高频混杂共振吸收在电离层加热过程中的重要贡献机制, 对于指导电离层加热实验设计具有指导意义。