高纬极区离子速度分布函数多项式解及非相干散射谱计算

为更准确描述高纬极区电离层离子分布函数, 分别采用弛豫碰撞模型和麦克斯韦分子碰撞模型描述玻耳兹曼方程的碰撞项, 通过求解两种模型下的输运方程, 分别得到两种模型基于麦克斯韦分布下离子分布函数的13矩近似和基于双麦克斯韦分布下离子分布函数的16矩近似. 进一步根据Sheffield理论, 利用两种模型下离子分布函数的13矩和16矩近似, 计算了非相干散射谱, 并对结果进行对比分析. 结果表明, 相对于弛豫碰撞模型, 麦克斯韦分子碰撞模型能更好地描述电离层E层中离子与中性成分的相互作用. 相对于离子分布函数的13矩近似, 16矩近似更适合描述由于电场增加导致的离子温度各向异性特征. 

Polynomial Solutions of the Ion Velocity Distributions and the Calculation of Incoherent Scatter Spectra in the High-latitude Auroral Ionosphere

In order to describe accurately ion velocity distribution in the auroral ionosphere, the relaxation collision model and the Maxwell molecule collision model is used to describe ion-neutral collisions of Boltzmann equation respectively. The expressions of the ion velocity distribution for 13-moment approximation based on the Maxwell and for 16-moment approximation based on the bi-Maxwell can be obtained by solving the transport equations of the Maxwell molecule collision model and the relaxation collision model respectively. According to Sheffield's theories, the incoherent scatter spectra are calculated using the ion velocity distribution of 13-moment approximation and 16-moment approximation for the relaxation collision model and the Maxwell molecule collision model respectively. Finally, the comparison of results of the incoherent scatter spectra between Maxwell molecule collision model and relaxation collision model are given. It is found that, the Maxwell molecule collision model is better than the relaxation collision model to describe the interaction between ion and neutral component in the ionosphere E layer. The 16-moment approximation is better than 13-moment approximation to describe the ion temperature anisotropy due to increased electric field.