The linear acceleration part of the SHINE project consists of two 3rd harmonic cryogenic modules which are operating at 3.9 GHz. Each of the cryomodules consists of eight 3.9 GHz 9-cell superconducting cavities. The SHINE specifications of the 3.9 GHz cavities are Qo >2.0e+9@13.1 MV/m and maximum accelerating gradient >15 MV/m. The 3.9 GHz cavities were treated with buffered chemical polishing (BCP) baseline combined with 2-step low-temperature baking surface treatment process to meet the specifications. In order to achieve the required performance, the BCP process had been optimized at the SHINE Wuxi surface treatment platform, especially the acid ratio. Vertical tests of all 3.9 GHz bare cavities treated with the optimized BCP process showed Qo up to 3.0e+9@13.1 MV/m and maximum accelerating gradient over 20 MV/m. The optimized BCP process applied to the 3.9 GHz cavities and related vertical test results were presented in this paper.

Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) is an x-ray FEL facility, consisting of an 8 GeV CW superconducting linac and 3 FEL undulator lines, covering the spectral ranges 0.4-25 keV. Photoinjector using VHF gun is one of the key part of the facility. The installation of the electron gun section of the SHINE injector has been completed in August 2023. RF conditioning and commissioning were carried out from September to December. In this paper, we will introduce the installation progress of the injector and show some commissioning results of the electron gun section.

Two 3.9~GHz cryomodules of sixteen cavities are required in the Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) linac. They are placed before the first bunch compressor to linearize energy distribution. A total of twenty-one 3.9~GHz 9-cell cavities including two prototypes were fabricated and tested. The first two prototypes reached a Q0 of 2.9x10^9 at 13.1 MV/m and a maximum accelerating gradient of 20.0 MV/m during the vertical test, with a large margin with respect to the SHINE specification. The first prototype was integrated into a small cryostat and horizontal tested. Batch fabrication of nineteen cavities started after the prototype qualification. The 3.9 GHz cryomodules are under assembling after the vertical tests. Horizontal tests are planned to start from mid of 2024. This paper will introduce the experience of the prototype development and mass production of the 3.9 GHz cavities.

According to the high repetition rate, high brightness and other operating characteristics of SHINE, the photocathode with high quantum efficiency, low emittance, and long operating lifetime is required to produce high-quality electron beam. After solving the problems of ultra-high vacuum acquisition, photocathode plug in vacuum transmission, and photocathode preparation process, the Cs-Te photocathode prepared on SHINE's photocathode preparation device based on Te intermittent and Cs continuous deposition method has a quantum efficiency greater than 10% under 265 nm light irradiation, and the quantum efficiency remains almost unchanged in the photocathode preparation device, photocathode suitcase, photocathode load lock system, and electron gun.

The SHINE project requires more than six hundred 1.3GHz cavities and sixteen 3.9GHz cavities for the superconducting accelerator. These cavities are from both domestic and foreign companies. The cavities fabricated in domestic companies requires correspond-ing capacity of surface-treatment. For the R&D of surface-treatment technology and mass production of SRF cavities, we have been constructing a new surface-treatment platform near Shanghai for SHINE project. In this paper, we report the design, construction, commissioning and operation of this platform.

SHINE project requires about 75 cryomodules with superconducting radio-frequency cavities to accelerate the beam to 8 GeV. Key components, technologies of cryomodule have been developing through prototypes and pre-series cryomodules. Up to now, several sets of cryomodule with high-Q cavities have been assembled and tested. We present the development status of SHINE cryomodules, including prototype cryomodules and the first ones for project.

In order to study the radio-frequency performance of superconducting materials at cryogenic temperature, we developed a TE-mode 3.9 GHz sample host cavity with a spherical bottom shape. A 11.5 cm diameter flat sample plate is enabled to attach to the cavity, with 9 cm diameter central area exposed to the RF field. In this paper, the design, fabrication and vertical test results of the sample host cavity will be presented.

The linear acceleration part of the SHINE project consists of two 3rd harmonic cryogenic modules which are operating at 3.9 GHz. Each of the cryomodules consists of eight 3.9 GHz 9-cell superconducting cavities. The SHINE specifications of the 3.9 GHz cavities are Qo >2.0e+9@13.1 MV/m and maximum accelerating gradient >15 MV/m. The 3.9 GHz cavities were treated with buffered chemical polishing (BCP) baseline combined with 2-step low-temperature baking surface treatment process to meet the specifications. In order to achieve the required performance, the BCP process had been optimized at the SHINE Wuxi surface treatment platform, especially the acid ratio. Vertical tests of all 3.9 GHz bare cavities treated with the optimized BCP process showed Qo up to 3.0e+9@13.1 MV/m and maximum accelerating gradient over 20 MV/m. The optimized BCP process applied to the 3.9 GHz cavities and related vertical test results were presented in this paper.