介绍了永磁移相器的控制精度对X射线自由电子激光（FEL）的影响, 分析其误差来源。针对传统运动控制系统检测过程复杂、手动操作精度低等缺点, 提出了基于改进高斯牛顿非线性参数估计法的自动校正系统, 阐述了校正理论与过程。利用该方法对欧洲X射线自由电子激光装置中的移相器做安装校正应用, 使得每台移相器在高磁场应力的环境下间隙位移达到μm级控制精度, 满足工程设计要求。

For long gap tunable undulator systems in free-electron laser (FEL), phase shifters with high control accuracy are required to ensure that the phases of the radiation field between two adjacent undulators matched with each other. We have studied the impact of control accuracy of phase shifter and analyzed its error sources. This study aims to improve the control accuracy of phase shifters and tries to overcome the shortcomings of the traditional calibration methods, such as complicated calibration procedure and low accuracy manual operations. Based on the improved Gaussian-Newton parameter estimation, this paper proposes an automatic error calibration system for phase shifters, including the preliminary concept and the algorithm. This method has been applied to installing and calibrating all the phase shifters of the European X-ray Free Electron (Euro-XFEL). The control accuracy of each phase shifter reaches micrometer-level in the environment of high magnetic forces, which satisfies the specified engineering design requirements.