用模拟退火法进行纯永磁波荡器磁块组合优化

Optimization of permanent-magnet undulator magnets ordering using simulated annealing algorithm

纯永磁波荡器由多个磁块组成,磁块的剩磁离散性会引起波荡器磁场误差,从而影响储存环工 作状态和自发辐射谱质量。在波荡器磁块安装之前,使用模拟退火法对磁块进行组合排序优化,可以使峰值场 强误差降低到10-4量级以下,磁场一次积分降低到10-6T·m量级,二次积分降低到10-6T·m2量级,优化 结果不依赖于初始状态的选择。给出优化的详细过程,提出了根据磁块剩磁快速计算波荡器峰值场强误差和 积分场的方法。

Pure permanent-magnet undulator consists of many magnets. The unavoidable remanence divergence of these magnets causes the undulator magnetic field error, which will affect the functional mode of the storage ring and the quality of the spontaneous emission spectrum. Optimizing permanent-magnet undulator magnets ordering using simulated annealing algorithm before installing undulator magnets, the first field integral can be reduced to 10-6 T &middot m, the second integral to 10-6 T &middot m2 and the peak field error to less than 10-4. The optimized results are independent of the initial solution. This paper gives the optimizing process in detail and puts forward a method to quickly calculate the peak field error and field integral according to the magnet remanence.