粒子加速器中激光跟踪仪控制网测量精度研究

Accuracy of Control Network Measured by Laser Tracker in Particle Accelerator

  • 摘要: 粒子加速器的高精度准直要求对测量技术提出很大挑战,由于激光跟踪仪具有大尺寸、高精度及三维空间测量的优势,因此需要开展激光跟踪仪对粒子加速器的测量精度研究。首先,针对激光跟踪仪的标称测量精度,介绍了激光跟踪仪标称测量精度的表达方法、测试方法,对标称精度指标的计算方法进行推导,并对其具体含义进行解释,为激光跟踪仪的测量应用及数据处理提供了理论基础。然后,以直线控制网为代表开展激光跟踪仪对粒子加速器控制网的测量方法和测量精度分析,在中国散裂中子源大科学装置直线加速器进行了实际测量,采用激光跟踪仪分两组在同一时间内进行观测,通过对控制网单组的平差精度以及两组的坐标对比分析,全面准确地评价其测量精度,发现200 m长直线控制网点位横向最弱精度优于0.2 mm。同时,以导线网为简化模型对直线控制网的精度进行理论估算,发现直线控制网中部点位横向精度与控制网长度的三次方开根号成正比,从而可快速推算出其他规模的直线控制网的的测量精度,为陆续建设的粒子加速器的准直精度分析以及准直方案决策提供指导。

     

    Abstract:
    Objectives The high accuracy alignment requirements of particle accelerators present a great challenge to measurement techniques. Due to the advantages of large volume, high precision and three-dimensional measurement of laser tracker, it is necessary to carry out the research on the measurement accuracy by laser tracker in particle accelerators.
    Methods First, this paper studied the measurement accuracy of laser tracker itself, introduced the expression and test method of the accuracy, derived the calculation formula and explained its specific meaning of rated accuracy, which provided a theoretical basis for the measurement application and data processing. Then, the linear control network was taken as a representative for the accuracy analysis of control network by laser tracker in particle accelerator, and a measurement activity was implemented in the linac of China Spallation Neutron Source facility, two groups were assigned to survey with different laser trackers during the same period.
    Results By analyzing the adjustment precision of each group and the coordinate deviations between the two groups, the weakest transversal accuracy of 200 m linear control network was confirmed and better than 0.2 mm. Moreover, in order to make a quick evaluation of the accuracy of linear control network, a method was proposed to estimate the accuracy with the network simplified to traverse network, and the rule of the weakest point accuracy was acquired that was proportional to the square root of the third power of length.
    Conclusions These studies can provide guidance for accuracy analysis and scheme design of alignment in particle accelerators.

     

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