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The beam position is the most important reference basis for the operation of synchrotron radiation light sources, particularly for commissioning the first-turn injection of fourth-generation light sources. To improve the accuracy of the beam position measurement, we analyzed methods for calculating the beam position, and a finite element calculation and the stretched wire calibration system were used to demonstrate the procedure. We proved the relationship between the coverage range, fitting order, scanning step size, and accuracy both theoretically and experimentally, which can provide a basis for selecting the appropriate fitting order for different operation stages of the accelerator. It was proved that the accuracy of beam position calculations using simplified polynomial coefficients is comparable to those without a simplified one, which can save resources for reading electronic processing. The testing results of a batch of beam position monitors (BPMs) were in good agreement with the finite element calculation results, and the small difference between the manufactured BPMs also proved that quality control was performed well, and it benefited from button sorting.

Beam position monitor (BPM) characterization has been widely studied at the synchrotron. The characteristic impedance of a stripline BPM was designed using a simulation and measured using the time-domain reflectometer method. The mechanical and electrical parameters of the feedthroughs with the buttons used for the BPMs were measured. Special care was taken in the analysis of the consistency of the four channels of the BPM. The feedthroughs were sorted based on their capacitance values. This paper presents the characterization results of the feedthroughs and BPMs. The electro-mechanical offsets were measured using the Lambertson method, and the calibration coefficients were measured using a stretched wire. The BPM differences introduced during mass production were determined by a statistical analysis of the measurement results.