Speaker
Description
The High Energy Photon Source (HEPS) is a fourth-generation synchrotron light source with a beam energy of 6 GeV and a circumference of 1.3km, currently under commissioning near Beijing, China. To achieve an ultra-low emittance of 35pm, the HEPS storage ring employs swap-out injection, significantly reducing the dynamic aperture requirements. However, the implementation of this scheme faces numerous physics and technical challenges. In particular, to meet the demands of time-resolved experiments, the injector need to prepare full-charge bunches of exceeding 15 nC, imposing stringent requirements on beam generation and acceleration.
To address these challenges, the HEPS team proposed a swap-out injection scheme based on high-energy accumulation in the booster ring, innovatively utilizing the booster also as a high-energy accumulation ring for recycling extracted bunches from the storage ring. This approach effectively alleviates technical bottlenecks in generating, capturing, and accelerating high-charge bunches at the low-energy end of the injector.
Since the proposal of this scheme in 2017, the team has spent seven years completing the physics design, development of key hardware components, and joint commissioning. On July 23, 2024, beam commissioning of the HEPS storage ring commenced, achieving first-turn injection within three hours. Through phased commissioning and optimization, the whole injection scheme was successfully demonstrated on January 2, 2025 and used in routine operation since then, supporting the commissioning of the HEPS storage ring, and laying the foundation for realizing the high-charge filling pattern.
This presentation summarizes the design philosophy, technical challenges, and beam commissioning experiences of this novel injection scheme, offering relevant insights for designs of future synchrotron radiation facilities and circular colliders.
