The accelerator-driven subcritical system (ADS) is the internationally recognized key technology of nuclear waste problem treatment, of which superconducting proton linac is an important part. With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences, the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac, which is called ADS Injector I. The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities with β 0.12. At the same time, the research work of various cavities with different β values and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator. The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic. As the only way to test the microwave performance of the superconducting cavity at low temperature, the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity. The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator.
This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I, including the system scheme design, process design, heat load analysis, 2 K superfluid helium obtaining method, system commissioning and operation, etc.
Results and Conclusion
The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624 W, which has reached the international advanced level. The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project, but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.