Targets for low-adiabat direct-drive-implosion experiments on OMEGA must meet rigorous specifications and tight tolerances on the diameter, wall thickness, wall-thickness uniformity, and presence of surface features. Of these, restrictions on the size and number of defects (bumps and depressions) on the surface are the most challenging. The properties of targets that are made using vapor-deposition and solutionbased microencapsulation techniques are reviewed. Targets were characterized using confocal microscopy, bright- and dark-field microscopy, atomic force microscopy, electron microscopy, and interferometry. Each technique has merits and limitations, and a combination of these techniques is necessary to adequately characterize a target. The main limitation with the glow-discharge polymerization (GDP) method for making targets is that it produces hundreds of domes with a lateral dimension of 0.7-2 mm. Polishing these targets reduces the size of some but not all domes, but it adds scratches and grooves to the surface. Solution-made polystyrene shells lack the dome features of GDP targets but have hundreds of submicrometer-size voids throughout the wall of the target; a few of these voids can be as large as ~12 mm at the surface.

Target is one of the essential parts in inertial confinement fusion (ICF) experiments. To ensure the symmetry and hydrodynamic stability in the implosion, there are stringent specifications for the target. Driven by the need to fabricate the target required by ICF experiments, a series of target fabrication techniques, including capsule fabrication techniques and the techniques of target characterization and assembly, are developed by the Research Center of Laser Fusion (RCLF), China Academy of Engineering Physics (CAEP). The capsule fabrication techniques for preparing polymer shells, glow discharge polymer (GDP) shells and hollow glass micro-sphere (HGM) are studied, and the techniques of target characterization and assembly are also investigated in this paper. Fundamental research about the target fabrication is also done to improve the quality of the target. Based on the development of target fabrication techniques, some kinds of target have been prepared and applied in the ICF experiments.

为提高惯性约束聚变（ICF）点火靶尺度（约2 mm）聚苯乙烯（PS）空心微球的球形度,研究了油相与外水相界面张力、初始油相质量分数和固化旋转流场转速对PS微球球形度的影响。结果表明,将双重乳液体系外水相中的表面活性剂聚乙烯醇（PVA）替换为聚丙烯酸（PAA）后,油相与外水相之间的界面张力增大了约10倍,PS空心微球的球形度显著提高,球形偏离度小于1 μm的微球比例由5%增加至约50%；但是,在较宽范围内改变油相初始质量分数及旋转固化流场转速,对PS微球球形度的影响并不显著,球形偏离度值小于1 μm的PS微球比例介于40%~60%之间。

在乳液微封装技术制备聚苯乙烯空心微球的工艺中，固化过程是决定微球球形度及壁厚均匀性的关键阶段。基于乳粒发生器制备内径(850±10) μm、壁厚(250±25) μm的复合乳粒，以25 ℃,45 ℃和65 ℃作为固化温度，考察了固化温度对微球球形度和壁厚均匀性的影响。结果表明，固化温度越低，界面张力越高，乳液固化速率越慢，微球球形度和壁厚均匀性越好。当固化温度为25 ℃时，批次微球中球形偏离值优于2 μm的微球产率为90%，壁厚偏差值优于2 μm的微球产率为40%，明显优于固化温度为45 ℃和65 ℃时微球的质量。

随着高功率激光器的飞速发展，ICF物理实验对聚苯乙烯(PS)-聚乙烯醇(PVA)双层空心微球的规格要求逐渐提高，直径要求将达到700～900 μm。针对该直径范围的PS-PVA双层空心微球，通过采用PS球臭氧化表面改性技术和搅拌桨叶轮结构优化技术，对传统乳液微封装法制备双层空心微球工艺进行了改进，臭氧化表面改性后PS固体核心发生憎水-亲水转变，提高了PS与PVA之间的作用强度; 搅拌桨叶轮结构优化，改善了体系容器内溶液流场均匀性，使得微球在整个体系中的运动相对平稳，从而初步制得了直径范围在700～900 μm的双层空心微球。

在采用乳液微封装技术制备聚-α-甲基苯乙烯（PAMS）空心微球的双重乳液固化过程中，为研究油包水（W1/O）复合液滴与外水相（W2）之间的密度匹配度对最终PAMS空心微球球形度的影响，理论研究了不同初始外径和油层厚度的复合液滴在不同固化时刻的平均密度；实验测量了W1/O复合液滴在固化过程中的油相质量分数及复合液滴的平均密度。研究结果表明：双重液滴固化过程的关键阶段为油相质量分数从20%增加至60%的过程。在双重乳液固化的关键阶段，当复合液滴与外水相的密度不匹配度由0.004 95 g/cm3降低至0.000 02 g/cm3时，微球球形偏离度值低于10 μm的PAMS微球粒子分数从14.3%提高至93.3%；调节外水相的组分来降低双重乳液与外水相在固化关键阶段的密度不匹配度,可显著提高最终PAMS微球的球形度。

在准静态条件和旋转流体场中采用乳液微封装技术制备约2 mm的大直径W1/O/W2乳粒，研究了有机相浓度和水溶性聚合物浓度对W1/O/W2乳粒稳定性的影响。从乳粒受力和变形的角度，探索了旋转流体场对W1/O/W2乳粒动力学稳定性的增强作用机制。研究表明：无论是在准静态条件下还是旋转流场中，乳粒稳定性都随聚苯乙烯浓度单一上升，随聚乙烯醇浓度呈现先上升后下降的趋势；相对于准静态条件，旋转流体场在一定条件下对大直径W1/O/W2乳粒的动力学稳定具有明显增强作用。

基于二次乳化技术产生W1/O/W2双重乳液, 采用乳液微封装技术制备聚-α-甲基苯乙烯(PAMS)空心微球, 研究了部分工艺参数对PAMS微球缺损形态和比例的影响。实验结果表明：薄壁微球的低强度导致了微球表面缺损。当微球壁厚一定时, 有3个因素影响缺损微球比例：W2相中聚乙烯醇质量分数、CaCl2质量分数和O/W2的相比, 当它们分别为1.0%, 1.5%, 0.01时, 薄壁(≤2 μm)微球的缺损比例低于40%, 球壳内也无气泡存在。