在电离层飞行的航天器近尾迹内电子数密度渐近解

本文讨论了航天器近尾迹流场电子数密度分布,给出无碰撞假设下等离子体绕带电圆盘流动的近尾迹流场渐近解。用匹配渐近展开法求解实际可能现出的三种情形的电子数密度分布。所得的摄动解对近尾迹流动的理论和数值研究有指导意义。

ON ASYMPTOTIC SOLUTION FOR ELECTRON DENSITY DISTRIBUTION IN THE NEAR-WAKE OF A SPACECRAFT IN IONOSPHERE

This study consists of two parts:an in-depth discussion about the electron density distribution in the near-wake of a spacecraft and asymptotic solutions for one-dimensinal collisionless steady-state plasma flow behind a charged disk. The methods of matched asymptotic expansions are used to get the di'stribution functions of electron number density for three possible cases in practice. These analytical forms are very useful to study the near-wake plasma flow interactions in the view of theory or numerical calculation. In section I. the governing equations and the boundary conditions are given for the general cases. In section II, according to the characteristics of the near-wake behind a charged disk, the mathmatical representation of the one-dimensionael model is given as follows:in Case A. in Case C. . For these three cases, singular perturbation method is employed to find an outer solution and an inner solution, and then, to propose the matching rulers that the inner solution and outer solution would obey. In section III, the asymptotic solution of the electron density distribution for the Case A is obtained using the methods of matched asymptotic expansions given in section II . The solutions for the Case B and Case C are given in section IV and V. respectively.