脉冲激光辐照空间碎片冲量耦合机理实验研究

The centimeter space debris removal by high power pulsed laser is viewed as a feasible method to mitigate its threat. The impulse coupling mechanism and rules of space debris irradiated by laser are the basic scientific problems in laser orbital debris removal. At present, the study is focused in the condition that the irradiated spot on planar target is much smaller than the plannar target size. However, in practice, the number of non planar space debris is in the majority and the laser beam size in the far field is fully enveloping the debris. Experimental study on impulse coupling mechanism of typical non planar space debris with the beam enveloping the target is investigated based on the scale down experiments in vacuum, including the characteristics of ablation plume injection and its acting mechanism to impulse coupling irradiated by laser in different incoming angles and the rules of impulse coupling influenced by three factors of laser incoming angles, shapes of space debris and laser parameters. The aim of the item is to discover the impulse coupling mechanism and rules when laser interacting with non planar space debris..The research results can provide a solid foundation for studying the scientific problems of the impulse coupling mechanism of non planar space debris enveloping by the laser beam ablation. The results also have great significances for enriching the theory of the interaction between the laser and the matter, and promoting the development and application of the laser space debris removal technology.

利用高能脉冲激光清除厘米级空间碎片被认为是减缓空间碎片危害的一种有效途径。激光辐照空间碎片冲量耦合机理及规律是激光清除碎片中的基础性科学问题。目前研究集中在激光烧蚀光斑尺寸远小于平面靶尺寸下的冲量耦合机理及规律，针对工程实际中非平面状碎片占多数，且远场到靶光斑尺寸大于碎片尺寸的情况，项目开展非平面状碎片在这种激光“全辐照”条件下的冲量耦合机理实验研究。通过真空环境下的缩比实验，研究激光不同入射角度“全辐照”条件下典型非平面状碎片的烧蚀羽流喷射特性及对冲量耦合的作用机理，研究激光入射角度、空间碎片形状和激光参数三种因素下的冲量耦合规律及影响，揭示激光与非平面状碎片的冲量耦合机理及规律。.研究成果可为激光“全辐照”非平面状空间碎片冲量耦合机理研究这一科学问题奠定基础，对于丰富激光与物质相互作用理论、促进激光清除空间碎片技术发展及工程应用也有重要意义。

脉冲激光辐照空间碎片冲量耦合特性及规律是激光清除碎片中的基础性科学问题。目前实验研究主要集中在激光烧蚀光斑尺寸远小于平面靶尺寸下的冲量耦合特性及规律，即激光小光斑点辐照下的特性，其光斑尺寸通常在百微米量级以下。项目开展了激光大光斑辐照空间碎片的冲量耦合特性实验研究，针对平面状典型材料碎片靶，研究了激光不同大光斑面积辐照下的羽流喷射特性及冲量特性，分析了等离子体核脱离靶面的时间以及冲量耦合的方向特性；进一步，基于可压缩流体动力学模型，计算分析了激光烧蚀压随时间演化过程的关系；研究结果表明大光斑辐照和小光斑辐照下的冲量耦合系数随激光功率密度的变化趋势相同，随着激光功率密度增加，冲量耦合系数先急剧增大然后逐渐减小，存在最优冲量耦合，但是相同激光功率密度下小光斑辐照对应的冲量耦合系数始终比大光斑辐照大。大光斑辐照下冲量耦合系数的变化规律主要受激光功率密度影响，受光斑尺寸影响较小，短波长激光有助于提高冲量耦合系数。针对典型非平面状材料碎片靶，研究了典型球形靶、楔形靶等非平面状碎片的等离子体羽流喷射特性，探求了激光大光斑辐照下羽流喷射对冲量耦合方向作用的物理规律，对比分析了同样激光条件下的平面靶与非平面靶的差异，分析了形成差异的物理机制。针对激光入射方向对羽流喷射特性的影响问题，获得了激光大角度入射辐照下，等离子体羽流喷射对冲量耦合的方向作用规律，进一步拓宽了激光入射不敏感角范围；并实验测量了激光大角度斜入射辐照条件下，典型非平面状碎片靶的冲量特性，得到冲量大小和方向与激光入射角度无关，冲量大小和方向与正入射时相同。在冲量耦合特性实验研究基础上，基于面积矩阵法建立了激光大光斑辐照空间碎片的冲量耦合预测模型，通过对模型中冲量耦合系数采用平面状碎片在大光斑辐照下的实验结果这一关键参数的修改，获得了更好的理论结果，与国外理论方法相比，模型结果更加与实验结果接近，提高了模型的适用性。