Self-developed Beam Position Monitor Electronics Developed for BEPC
With support from the Major Achievements Cultivation Program of the Chinese Academy of Sciences, the Beam Instrumentation (BI) Group of the Accelerator Division of the Institute of High Energy Physics has completed a new upgrade of beam position measurement (BPM) electronics in the BEPCII storage ring, and all 98 sets of imported analog electronics have been replaced by self-developed electronics with independent intellectual property rights. After nearly a year of online operation at the BEPCII storage ring (Sept. 2021–Jul. 2022), the resolution of the self-developed electronics is better than 0.1 μm and the beam orbit stability is better than 10 μm @ 72 hours, fully satisfying or even exceeding the experimental requirements of the BEPCII collision mode and synchrotron radiation mode.
(The beam stability of BEPCII is much worse than that of third- or fourth-generation light sources, so the above beam test results do not represent the best performance of the self-developed electronics. That is to say, the test results would be much better if we could test the electronics in third- or fourth-generation light sources.)
BPM electronics are essential for beam diagnostics, and their resolution and long-term operational stability directly affect the accelerator's beam orbit and operational stability. For a long time, the key technologies used in BPM electronics have been monopolized by a foreign company. The price is high, the software is not open, and such electronics are difficult to upgrade and maintain, which affects secondary development and high-end applications.
After more than seven years of hard work, the BI Group of the Accelerator Division has overcome many technical difficulties, iteratively upgraded several versions of the electronics, and developed an electronic automatic testing system for BPM electronics. Based on this work, the BI Group solved all the problems from prototype development to batch application and grasped key technology. Twenty sets of single-pass, self-developed electronics were put into operation in the BEPCII linac in 2019. After that, 98 sets of “collision mode and synchrotron radiation mode”-compatible BPM electronics have been gradually applied to the BEPCII storage ring. At present, self-developed BPM electronics have also been installed in the linac of the High Energy Synchrotron Radiation Photon Source (HEPS). Next, all of the BPM systems for the HEPS booster and storage rings will be equipped with self-developed BPM electronics for beam orbit measurement and control. At the same time, the BI Group will work with accelerator physicists and operators to expand self-developed electronics to high-end applications research.
This project is also supported by the Fund of the Youth Innovation Promotion Association of the Chinese Academy of Sciences and the HEPS-TF project.