The Beijing Synchrotron Radiation Facility (BSRF) successfully realized top-up injection on July 14, 2015. Its beam intensity was 250mA±0.1mA, reaching the world advanced level.

The realization of top-up mode operation is an important milestone for BSRF to further improve its performance. During the top-up injection from July 14 to 16, all the beam-lines and stations were open to users, who praised the stable light and the excellent experiments.

Top-up is the operation mode that many synchrotron light sources have taken in recent years. It has many advantages. Under this mode, facility is able to always run at higher intensity and higher average luminosity, and is not limited by beam lifetime. As a result, the user efficiency is simultaneously upgraded. In addition, the constant beam currents and correspondingly constant synchrotron radiation power make the heat load of the accelerator and beam-line components constant, greatly increasing the stability of the beam orbit and synchrotron radiation light spots.

It is not an easy job, which embodies the hard efforts of the operation team and the stability of the BEPCII hardware. Since June 2014, the BEPCII operation staff started to study the possibility of top-up mode. Only after careful theoretical analysis and many beam tests, could top-up mode operation on BSRF be realized. As the BEPCII Linac is for multi-purpose, it provides beam to the storage ring and to the test beam facility as well, the hard part is that both cannot be done at the same time.

This round of top-up mode operation was finished on July 16th, when the regular operation mode with injection four times a day was restored.