| Before the construction of the magnetic confinement fusion reactor,it is necessary to carry out the overall performance evaluation of superconducting magnet system,and research on the stability,reliability and safety of the magnet system.As the carrier of current,superconducting conductors’ performance and stability needs to be evaluated through experimental testing of short samples before formal production,so as to meet the requirements of future fusion reactor.At present,the maximum magnetic field of the toroidal field of China Fusion Engineering Experimental Reactor(CFETR)independently designed by China is about 15 T.However,the few superconducting conductor test systems in the world at present,such as SULTAN,EDIPO,SSTF,FRESCA,etc.they all have the problems of low magnetic field,limited test space,limited test time and high test cost.Therefore,in order to meet the demand for superconducting conductor testing in future fusion reactors,the conductor performance research facility has been proposed as an important device for the comprehensive research facility of the fusion reactor in the national "13th Five-Year Plan",which can provide a central magnetic field of up to 16.5 T,with a uniformity of the magnetic field of the test area of more than 95%..The device will be the world’s superconducting conductor performance research device with the highest field strength and the largest uniform area size when it is completed.The conductor performance research facility consists of a host system,a power supply system and a cryogenic support system.As the most core component of the host system,the background superconducting magnet has a large volume,complex structure and harsh operating conditions.Strict cryogenic cooling design and thermal analysis are required to ensure stable and safe operation of background magnet.The main research object of this paper is the background superconducting magnet of the conductor performance research facility.According to the system structure of the platform,the components of its heat load are analyzed,and the heat load in the 4.3 K temperature zone of the host system in different operation modes is calculated and analyzed,including the steady state heat load and transient heat load.According to the structure of the facility,the components of heat load are analyzed,and 4.3 K heat load of the host system is calculated and analyzed in different operation modes,including the steady state heat load and transient heat load.Accurate analysis of the heat load is the basis of cooling design,which can check whether the power of the refrigerator meets the requirements of the device operation and provide a basis for the design of the cooling system.According to the design guidelines of the magnet cooling loop,the length limitation of the cooling channel was analyzed.Designed and carried out experiments to measure the friction factor of the conductor,investigated the influence of heat treatment,strand plating,helium inlet and outlet on the friction factor.The design of the cooling channel of the magnet was carried out,analyzed and determined the inlet and outlet parameters of supercritical helium during the operation of the magnet.The cooling loops of the facility was designed,and the cryogenic piping was integrated through a 3D modeling system.Coil cooling loops flow distribution experiments were carried out to verify the feasibility and accuracy of the design.Based on the Comsol platform,the paper proposes a model to satisfy the analysis of the cooling process of superconducting magnets,and uses the parameters during the cooling period of the EAST TF coil from March 4,2023,to March 25,2023,to validate the accuracy of this model.Using this model,the background magnet of the conductor performance research facility was modeled and calculated,and a cooling scheme was proposed,which gave the cooling curves of the device under different parameters,as well as the temperature distribution of each part of magnet and mass flow rate of cold helium gas.The calculation results provide theoretical guidance for the cooling experiment.In this paper,for the problem of quench in CICC-type superconducting magnets,a quasi-3D quench analysis model is proposed based on the COMSOL platform,and the accuracy of the model is verified by comparing with the calculation results of Gandalf and THEA.Based on this quasi-3D model,several cooling loops that operate under the worst conditions in the high,medium and low field coils are modeled and analyzed.Important parameters such as the stability margin of the magnet,the temperature evolution of the coil after quench and the maximum quench pressure and hotspot temperature are obtained,which provide an important reference for the quench protection of the magnet. |
