加热电离层生成不均匀体的理论及模拟研究

Theoretical and numerical study on HF-induced ionospheric irregularities

针对均匀和平面分层电离层背景，分别建立了描述大功率高频（HF）泵波加热电离层产生不均匀体的物理模型，从理论上解释了加热过程中不均匀体的生成主要是有质动力和热压力共同作用的结果。基于均匀电离层背景下加热电离层生成不均匀体的理论，通过数值模拟得到了加热导致电子密度不均匀体的空间分布。模拟结果表明，电子密度扰动在泵场方向上的特征长度为1km量级，在垂直于泵波电场方向上的特征长度为10～20m；这与电离层加热实验观测到的不均匀体纵向特征长度一般为千米量级、横向特征长度一般为10m量级的结论是相符的。另外，数值模拟得到的电子密度“空洞”和“稠团”的交替分布，可以解释加热过程产生的无线电波自聚焦效应。

This paper presents theoretical models for the formation of HF-induced ionospheric irregularities under both homogeneous and stratified ionosphere backgrounds. It proves theoretically that pondermotive force and thermal pressure play a lead role in the evolution of artificial irregularities during ionospheric heating. Based on the physical model for homogeneous ionosphere, spatial structures of HFinduced ionospheric irregularities are numerically obtained. The results demonstrate that electron density turbulences exhibit a typical scale of more than one kilometer in the pump field direction and of 10 to 20 meters in its perpendicular direction. These results match well with the experimental observations that artificial ionospheric irregularities usually hold a transverse scale of 10 meters and a longitudinal scale of one kilometer. The numerically obtained alternant structure of electron depletion and enhancement can also interpret self-focusing effect of radio waves during ionospheric heating processes.