Optimizing the lattice design of a diffraction-limited storage ring with a rational combination of particle swarm and genetic algorithms*
Optimizing the lattice design of a diffraction-limited storage ring with a rational combination of particle swarm and genetic algorithms*
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DOI：
10.1088/1674-1137/41/2/027001
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发表时间：
2016-05
影响因子：
3.6
通讯作者：
Y. Jiao;G. Xu
中科院分区：
文献类型：
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作者：
Y. Jiao;G. Xu
在紧凑型多弯消色差元件组成的限衍射存储环（DLSR）设计中，由于元件参数的非线性极大且可调范围有限，难以同时实现超低发射度和满意的非线性性能。然而，以高能光子源（HEPS）为例，我们证明了通过粒子群优化（PSO）和多目标遗传算法（MOGA）的连续迭代实现可以探索DLSR设计的潜力。结果表明，在混合MBA晶格下，HEPS的自然发射度达到约50 pm是可行的。同时，采用轴向纵向注射方案，实现了足够的环接受梁积累。特别是，对于具有许多优化变量和局部最优解的探索性多目标问题，PSO和MOGA的合理组合在逼近真正的全局最优解方面比单独使用它们更有效。
In the design of a diffraction-limited storage ring (DLSR) consisting of compact multi-bend achromats (MBAs), it is challenging to simultaneously achieve an ultralow emittance and a satisfactory nonlinear performance, due to extremely large nonlinearities and limited tuning ranges of the element parameters. Nevertheless, taking the High Energy Photon Source (HEPS) as an example, we demonstrate that the potential of a DLSR design can be explored with a successive and iterative implementation of the particle swarm optimization (PSO) and multi-objective genetic algorithm (MOGA). It turns out that with a hybrid MBA lattice, it is feasible for the HEPS to attain a natural emittance of about 50 pm.rad, and meanwhile, realize a sufficient ring acceptance for beam accumulation with an on-axis longitudinal injection scheme. Particularly, this study indicates that a rational combination of the PSO and MOGA is more effective than either of them alone in approaching the true global optima, for an explorative multi-objective problem with many optimizing variables and local optima.