Simulation study on thermal performance of two turns helium cryogenic oscillating heat pipe for superconducting accelerator

Purpose In recent years,with the further development of superconducting technology,superconducting devices have been applied in particle accelerators and synchrotron radiation light source devices.As a new type of heat transfer structure,helium cryogenic oscillating heat pipe can be used to balance local hot spots in superconductors and improve heat transfer performance.Methods In this paper,a two-dimensional two-turns helium cryogenic oscillating heat pipe model is established.The flow performance of helium cryogenic oscillating heat pipe was analyzed by CFD simulation.Results and conclusion The results show that the development of flow pattern in the helium cryogenic oscillating heat pipe first forms bubble flow under the heating of the evaporation section,and then gradually forms slug flow and annular flow.The process consists of initial stage,transition stage and running stage.In the running stage,the effective thermal conductivity of COHP oscillates around 15,000 W/(m·K).

2 K superfluid helium cryogenic vertical test system for superconducting cavity of ADS Injector I

Purpose 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 withβ0.12.At the same time,the research work of various cavities with differentβvalues 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.Methods 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 1.624W,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.