大量太空垃圾对人类航天活动构成了巨大威胁，激光空间碎片清除是一种非常重要且有效清理太空垃圾的方法。迄今为止，国内外主要围绕两方面，即：激光与空间碎片的冲量耦合特性、激光作用下碎片的减速降轨特性，开展相关实验和理论研究。然而，地基空间碎片清除不可避免地会遇到强激光大气传输问题，而强激光大气传输出现的自聚焦和群速度色散效应、以及大气湍流等因素对光束质量的影响是十分显著的。因此，要将地基激光空间碎片清除技术用于实践，必须弄清楚空间碎片清除中宽带脉冲激光大气传输相关物理问题。本项目以清除空间碎片所需激光能量涉及的两个重要物理量（脉宽、束宽）为出发点，研究宽带脉冲激光在地球随高度变化的非均匀大气中传输的自聚焦效应、群速度色散效应，以及激光带宽、啁啾、空间相干性、高阶模、环状分布、像差和大气湍流等物理因素对光束质量的影响，提出有利于激光空间碎片清除的途径，为地基激光空间碎片清除提供理论基础和计算依据。

A large number of space-debris poses great threat to human space activities. The laser space-debris cleaning is an important and effective method. Until now, the main two aspects of experimental and theoretical research have been carried out, namely, the impulse coupling characteristics between laser and space-debris, and de-orbit characteristics of space-debris due to laser. However, the problem of high-power laser beam propagation through the atmosphere will be encountered in laser space-debris cleaning. Furthermore, the effects of self-focusing, the group velocity dispersion and the atmospheric turbulence, etc. on the beam quality are very significant. Therefore, the physics problems of broadband laser pulses propagating in the atmosphere must be resolved before the technology of ground-based space-debris cleaning is used in practice. In this project, we begin the research with two important parameters (pulse duration, beam width) related to the laser power required for space-debris cleaning. We study the self-focusing effect and the group velocity dispersion effect in the inhomogeneous atmosphere, and study the influence of pulse duration, beam spatial coherence, beam higher-order mode, beam annular distribution and aberration on the beam quality. We provide the methods that are beneficial to space-debris cleaning. The results obtained in this project will provide basic theories and calculation methods for the space-debris cleaning.