六极铁作为高能同步辐射光源(High Energy Photon Source,HEPS)储存环八铁单元的重要部件之一,其技术工艺较为复杂,对加工精度和中心引出精度要求都很高.本文对HEPS六极铁的机械中心引出标定方案进行了研究,利用极缝偏差角对常规标定坐标系进行旋转,使三个极缝面更接近理论位置,从而减小磁铁主场斜分量;对每块磁铁进行两次机械中心标定,极缝间距的实测值与设计值的标准偏差在0.015 mm,坐标系旋转前后的基准点偏差标准值为0.09 mm,旋转角最大可达0.6 mrad.这种考虑极缝偏差角的建系方法可以提高标定的精度,能为实际工作中同类型、准直精度有相同要求的设备标定提供参考,有利于加速器装置的顺利安装,对加速器准直测量具有十分重要的意义.
[Background]Sextupoles are an important component of storage ring octonal unit in high energy synchrotron radiation sources.They require complex technological processes and precise center extraction.Therefore,it is necessary to find out the most reasonable calibration scheme for the mechanical center.[Purpose]This study aims at the calibration scheme for the mechanical center extraction of high energy photon Ssurce(HEPS)sextupoles,and obtaining the corrected mechanical central coordinate system.[Methods]The method of directly measuring the reference plane of the sextupole was adopted for the mechanical center calibration of magnets.By rotating the conventional calibration coordinate system with a given pole seam deviation angle,the three polar seam surfaces were brought closer to the theoretical positions to decrease the main diagonal component of the sextupoles.The mechanical center calibrations were performed twice for each hexacode iron to further reduce the impact of the polar seam error.[Results]The calibration results show that the calibration repeat accuracy is 0.005 mm for the sextupole.The standard deviation between the measured value and the design value of the pole seam spacing is 0.015 mm.Additionally,the standard deviation of the reference point before and after the rotation of the coordinate system is 0.09 mm,with a maximum rotation angle of 0.6 mrad.[Conclusions]The calibration scheme of this study can be used to improve the calibration accuracy and provide reference for the calibration of similar equipment.It ensures smooth installation of accelerator devices and is of significant importance for accelerator collimation measurements.