The application of digital technology in BEPCII RF system

Background The Beijing Electron Positron Collider (BEPCII) is a high-brightness collider and operates in compatible mode of synchronous light source. This summer, BEPCII spare cavity, which was all made in China, had been put into BEPCII operation, and the LLRF system for the spare cavity was also upgraded at the time. Purpose The purpose is to stably control the amplitude and phase of the spare cavity and apply digital technology to achieve some intelligent functions. Methods The digital method is applied in the superconducting cavity feedback control of the accelerator and it introduces the digital technology of the RF low-level control system that has been stably applied to the BEPCII spare cavity operation. In addition, some functions such as quench detector and input protection as well as horizontal test have been realized in the RF system operation. Results The amplitude and phase stabilities of cavity voltage with beam in the digital LLRF have reached ± 0.09% (RMS) and ± 0.055^∘ (RMS), respectively. Conclusion The BEPCII spare cavity with digital LLRF system has been stably operated for 2 months. The DLLRF system has been reliable and stable, and the performance of the spare cavity with beam was very good.