The upgraded Advanced Photon Source (APS), a U.S. Department of Energy Office of Science user facility located at Argonne National Laboratory, is now the world’s first synchrotron light source to use a multi-bunch swap-out method of replenishing the electron beam in its storage ring.
On April 29, 2024, Argonne’s Accelerator Systems Division (ASD) team successfully demonstrated multi-bunch swap-out injection of a stored beam of electrons. Regular injections into the ring are required because electron beams have a limited lifetime. Electrons scatter as they circulate, and eventually the beam is depleted and must be replenished. In the late 1990s, the APS pioneered top-up injection, which provides nearly constant stored beam current to X-ray experiments by “topping up” electron bunches that have lost electrons. This has become a standard operation mode for light sources worldwide.
Read more on APS website
Image: The near constant storage ring current is the result of electron bunches being injected through the booster to storage ring transfer line (BTS) while a corresponding electron bunch in the storage ring is kicked out into the swap-out dump.