Development And Studies Of Storage Ring Beam Position Monitor System At HLS Ⅱ

The beam position is one of the important parameters of accelerators, which is significant in machine state judgment and performance evaluation. As a subproject of the upgrade project of the Hefei Light Source (HLS), a new beam position monitor (BPM) system has been developed to provide an important beam diagnostic tool for the storage ring. A series of tests and studies has been carried out under existing conditions.Firstly, the principles and methods of the beam position monitor are briefly described, and then there is a detailed introduction about the button electrode design, the data acquisition system development, tests and application for the new system.According to the upgrade project requirements, HLS II storage ring’s vacuum chamber will change from round to octagon. Some work are finished for this improvement, including the BPM electrodes mechanical parameters simulation and optimization, button space determination, preliminary electrical characteristics estimation, BPM position sensitivity calculation with the difference/sum ratio and the log-ratio method, the fitting formula for the electrical position and the button sum signal. The new BPM is tested and calibrated offline.The structure of the Libera Brilliance and the Bergoz electronics is analyzed; the key performance parameters of Libera Brilliance are tested offline. A LabVIEW based automated test platform is built to test the beam position resolution and the beam dependence of the instrument. the EPICS package is optimized to fit the HLS Ⅱ storage ring; an IOC is established in the Libera to release the beam data from FPGA; a Soft IOC running on a server gets the button signals by LAN and recalculates the beam position with the log-ratio method followed by signal processing and data analysis; An integral operator interface has been finished with EDM and CSS BOY.Some studies have been finished on the original storage ring with Libera Brilliance, including the accuracy and stability of the Libera, the measurement of tune, beam current, life time, bunch current and the button gain coefficient. The results showed good performance and provided important data for the operation of the new storage ring.Finally, the entire system is summarized; the current problems are proposed and the future work is introduced.