HEPS Is Standing Out

Nearly 3 years after the groundbreaking ceremony for the High Energy Photon Source (HEPS) in June 2019, the HEPS buildings are standing out in Huairou Science City in Beijing (Figure 1). The design of the HEPS building complex looks like a magnifier with the storage ring as its head and auxiliary buildings as its handle. This is symbolically fitting, as HEPS is designed to enable structural details of matter to be magnified and observed by high energy, high brilliant, and high coherent X-rays. The goal for the emittance of HEPS is less than 60 pm rad. In order for the ground buildings to house the accelerator and beamlines of this 4th-generation 6 GeV machine, earth was evacuated 4 m deep. It was refilled with plain concrete to form a stable slab. The preliminary vibration measurement result of this huge concrete slab has been positive, and the buildings housing the three long beamlines in Phase I are also taking shape. As a result of engineering challenges involving the accelerator components, the storage ring lattice and injector design were modified and frozen. Numerous prototypes were tested, validated, and launched into production. Manufacturing of pre-series components began, including accelerating structure, pulse compressor, magnet girder, RF solid-state amplifier, 166.6 MHz superconducting RF cavity, digital BPM processor, vacuum chambers, photon absorbers, and vacuum instruments. The pre-series manufacturing of magnets is underway for the high-gradient quadrupoles, dipole-quadrupoles, sextupoles, octupoles, and fast correctors. Following the successful validation of pre-series equipment, production of the main series of components for HEPS started. Tremendous progress was made in 2021 on the procurement of the accelerator components for the HEPS’ storage ring, booster, and LINAC (Figure 2). All booster magnets have been completed and 75% of them have been measured. Most types of storage ring magnets have been prototyped and 25% of the sextupoles have been measured. The setup of a Non-Evaporable Getter (NEG) coating for the massive storage ring vacuum chambers has been built, and some NEG coating testing runs are already done (Figure 3). Six types of insertion devices were designed for the Phase I beamlines. The manufacturing of the in-air Insertion Devices (IDs) is nearly done, after assembly and factory acceptance testing, and magnetic tuning was scheduled (at press time) to start soon. The mass production of the in-vacuum IDs, including Cryogenic Permanent Magnet Undulators (CPMUs) and In-Vacuum Undulators (IVUs), is in progress. The prototype 166.6 MHz 260 kW RF solid-state amplifier has Figure 1: The HEPS building complex. The circumference of the largest ring building is around 1500 m. The extension buildings from this ring will contain three long beamlines. Inset is the logo of the HEPS, reflecting its magnifier design.