Stable generation of high-quality beam by 3-GeV low-emittance linear accelerator in NanoTerasu

The construction of a low-emittance 3-GeV linear accelerator as an injector system of a new high-brilliance synchrotron radiation facility “NanoTerasu” was completed in January 2023. After beam commissioning of the accelerator complex for several months, the synchrotron radiation for user experiment was provided in April 2024 as planned [*]. The 3-GeV compact linear accelerator consists of 40-MeV injector system and C-band accelerator. The electron beam with a bunch charge of more than 0.5 nC and normalized emittance of less than 2 mm mrad is generated from an electron RF gun system with a gridded thermionic cathode at a “transparent” grid condition [**]. In the 40-MeV injector system, the bunched beam with a bunch length of 5 ps and normalized emittance of less than 10 mm mrad is generated. In usual operation, the bunched beam is accelerated up to 3 GeV and injected stably into the storage ring. In this presentation, we report on the establishment of beam adjustment by tuning RF amplitude and phase. We also report on the beam performance obtained, including beam stability, and comparing the design beam envelope and measured beam optics in the linear accelerator.