Development of an automatic calibration system for beam position monitor

Abstract

BackgroundBeam position monitor (BPM) is an important beam measurement component of accelerators, and it generally needs to be calibrated before online operating. High energy photon source (HEPS) and upgrade of Beijing electron positron collider (BEPCII) will need a large amount of BPM, which brings challenges to the calibration work.PurposeThis study aims to design and implement an automatic BPM calibration system for raising calibration efficiency and improving the accuracy of BPM measurement after calibration.MethodsFirst of all, an analog beam generating device, precision motion and support device, signal processing electronics and industrial computer were employed to compose the hardware of the calibration system. Then, the control software was programmed by Python to realize automation of the calibration, and the binary polynomial regression algorithm was used to determine the probe calibration coefficient. Finally, the appropriate calibration parameters were optimized by the combination experiments with sufficient raw data, and the influence of calibration range, number of calibration points and fitting order on calibration accuracy were analyzed.ResultsThe calibration system can automatically complete the BPM probe calibration. The BPM accuracy can reach 40 μm over the entire calibration range, and 7 μm in the local linear region.ConclusionsThe calibration system of this study meets application requirements and achieves the expected function. The measurement accuracy of the calibrated BPM is related to factors such as the order of the polynomial, the calibration range and the selection of calibration points.

Keywords

• beam position monitor
• automatic calibration system
• epics
• data analysis