Tian Chao, Chen Jia, Zhang Bo, Shan Lianqiang, Zhou Weimin, Liu Dongxiao, Bi Bi, Zhang Feng, Wang Weiwu, Zhang Baohan, Gu Yuqiu
Opt Express. 2015 May 4;23(9):12362-72. doi: 10.1364/OE.23.012362.
The uniformity of the compression driver is of fundamental importance for inertial confinement fusion (ICF). In this paper, the illumination uniformity on a spherical capsule during the initial imprinting phase directly driven by laser beams has been considered. We aim to explore methods to achieve high direct drive illumination uniformity on laser facilities designed for indirect drive ICF. There are many parameters that would affect the irradiation uniformity, such as Polar Direct Drive displacement quantity, capsule radius, laser spot size and intensity distribution within a laser beam. A novel approach to reduce the root mean square illumination non-uniformity based on multi-parameter optimizing approach (particle swarm optimization) is proposed, which enables us to obtain a set of optimal parameters over a large parameter space. Finally, this method is applied to improve the direct drive illumination uniformity provided by Shenguang III laser facility and the illumination non-uniformity is reduced from 5.62% to 0.23% for perfectly balanced beams. Moreover, beam errors (power imbalance and pointing error) are taken into account to provide a more practical solution and results show that this multi-parameter optimization approach is effective.
压缩驱动器的均匀性对于惯性约束聚变（ICF）至关重要。本文考虑了在由激光束直接驱动的初始印刻阶段，球形靶丸上的辐照均匀性。我们旨在探索在为间接驱动ICF设计的激光装置上实现高直接驱动辐照均匀性的方法。有许多参数会影响辐照均匀性，例如极向直接驱动位移量、靶丸半径、激光光斑尺寸以及激光束内的强度分布。提出了一种基于多参数优化方法（粒子群优化）来降低均方根辐照不均匀性的新方法，这使我们能够在大参数空间内获得一组最优参数。最后，将该方法应用于改善神光III激光装置提供的直接驱动辐照均匀性，对于完美平衡光束，辐照不均匀性从5.62%降低到了0.23%。此外，考虑了光束误差（功率不平衡和指向误差）以提供更实际的解决方案，结果表明这种多参数优化方法是有效的。
