Study on High-Time-Resolution Beam Loss Monitoring Technology for Hefei Light Source II

Abstract: [Background]: Beam loss monitoring is essential for the stable operation of the Hefei Light Source II(HLS-II). Accurate measurement of bunch-by-bunch beam loss and position information helps to diagnose beam instabilities and optimize accelerator performance. [Purpose]: This study aims to monitor and analyze the beam loss characteristics during the operation of the HLS-II. [Methods]: A high-time-resolution beam loss and bunch position synchronization monitoring system was developed using a scintillator detector, a strip-electrode beam position monitor (BPM), and a high-speed oscilloscope. The accuracy of the system’s beam loss pulse waveform output was validated by comparing simulated and measured waveforms. An asymmetric Gaussian fitting method was employed to extract characteristic parameters of the beam loss pulses. Using the HOTCAP (a software package for high-speed oscilloscope-based three-dimensional bunch-by-bunch charge and position measurement) technique, the bunch-by-bunch charge and position information were extracted from BPM signals. The bunch indexing between beam loss data and BPM data was successfully aligned based on the unique filling pattern of the HLS storage ring, achieving data synchronization. [Results]: This system was used to monitor beam losses during both the transient injection process and steady-state operation of the HLS-II. The results indicate that, during steady-state operation, the bunch-by-bunch beam loss exhibits a significant correlation with the charge distribution, consistent with the theoretical expectations of random beam loss. During the transient injection process, a unique beam loss phenomenon was observed for the first time: significant beam loss occurred simultaneously in the injected bunch and the 14th stored bunch following it. [Conclusions]: The measurement system is capable of synchronously acquiring bunch-by-bunch charge, transverse position, longitudinal position, and beam loss data from the HLS-II, providing strong technical support for diagnosing beam instabilities and optimizing accelerator performance.