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在直接驱动惯性约束聚变中,实现靶丸均匀辐照对靶丸压缩特性至关重要,通常要求靶丸表面辐照不均匀度小于1%.现有很多优化高功率激光装置均匀辐照性能的光束排布方案,但受到实际入射光束参量的限制,系统均匀辐照性能难以实现最优化.由于初始辐照不均匀度对靶丸对称压缩特性至关重要,为进一步提高靶丸初始辐照的均匀性,并增加系统对打靶过程中由于靶丸直径变化引起的辐照不均匀的宽容度,从而实现靶丸的中心对称压缩,本文对靶丸表面光束的辐照不均匀度进行了数学分析,并研究了不同入射光束参量下的单光束因子项及其对靶丸均匀辐照的影响.结果表明:对于已知的光束排布结构,存在最优的入射光束参量,使辐照均匀度最高.证明了通过优化入射光束参量提高系统均匀辐照性能的可行性.此外,研究表明单光束因子项与几何因子项存在一定的匹配关系,可通过分析几何因子项的特征,求取与之匹配的单光束因子项,进而获得最优的入射光束参量.本工作为直接驱动靶丸均匀辐照系统的设计和优化提供了一种有效的方法.
In the direct-drive inertial confinement fusion, the uniform irradiation of the target is crucial to the compression characteristics of the target, which usually requires less than 1% of the surface irradiation unevenness of the target.There are many methods to optimize the uniform radiation performance of the high-power laser However, due to the limitation of the actual incident beam parameters, it is difficult to optimize the uniform irradiation performance of the system.Because the initial irradiation uniformity is very important for the symmetrical compression of the target, in order to further improve the initial irradiation of the target Uniformity, and increase the tolerance of the system due to the uneven irradiation caused by the change of the diameter of the target during the shooting process, so as to realize symmetric compression of the center of the target. In this paper, the mathematical analysis of the irradiation unevenness of the target surface beam The effects of different incident beam parameters on the single beam factor and its effect on uniform irradiation of target pellets were studied.The results show that there is an optimal incident beam parameter for the known beam arrangement, The highest.The feasibility of improving the uniform radiation performance of the system by optimizing the incident beam parameters is proved.In addition, the research shows that there is a certain match between the single beam factor and the geometric factor , We can get the optimal incident beam parameters by analyzing the characteristics of the geometric factors and obtaining the matched single-beam factors.This work provides a method for the design and optimization of direct-driven uniform irradiation system effective method.