Search

BackgroundSextupoles 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.PurposeThis 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.MethodsThe 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.ResultsThe 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.ConclusionsThe 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.

BackgroundCompared with 2D+1D adjustment, three dimensional adjustment has a more rigorous theoretical basis. However, when the unconstrained three dimensional adjustment is applied to the observation values processing of the accelerator alignment control network, serious error accumulation will occur and resulting in obvious distortion of the results.PurposeThis study aims to expound the ways and characteristics of three dimensional adjustment error accumulation for accelerator alignment control network.MethodsFirstly, based on the layout of accelerator alignment control network and the moving station measurement method of laser tracker, the three dimensional adjustment mathematical model was analyzed, and the least-squares collocation theory was used to clearly explain the error propagation. Secondly, the characters of laser tracker measurement accuracy, station positioning and orientation accuracy and single station measurement error propagation were studied by analyzing the laser tracker 3D coordinate measurement model, measurement point error model and simulation measurement experiments. Finally, adjustment calculation of the linac control network was verified by simulation measurement, and two error accumulation suppression methods were tested.ResultsThe source and propagation mode of error accumulation are explained theoretically, and verified by simulation calculation, so are the serious error accumulation of elevation and lateral errors in three dimensional adjustment of control network in accelerator.ConclusionsProviding high-precision point coordinate constraint for three dimensional adjustment can effectively suppress error accumulation, and providing high-precision orientation constraint for station coordinate system can also achieve the effect of suppressing error accumulation.