| Superconducting joint is one of the core components of superconducting magnet.It can connect two superconducting coils,so that they can maintain the superconducting state and realize current transmission.The resistance of the superconducting joint determines the attenuation rate of the magnet,and is an important index to evaluate the performance of the superconducting magnet.Therefore,accurately measuring the resistance of superconducting joints is the key to evaluating the quality of superconducting joints,which requires a superconducting joint resistance testing system.The subject comes from the national key research and development program: the development of the high magnetic field superconducting magnet system of the cryogenic high magnetic field comprehensive physical property measurement instrument.In this paper,the superconducting joint used in 9T conduction cooled superconducting magnet is designed and fabricated,and the software and hardware test system of superconducting joint resistance is designed and built.The following studies were mainly conducted:In the application of 9T conduction cooled superconducting magnet superconducting joints,it is planned to prepare superconducting joints with small size,avoiding flux jump and high cooling speed.The superconducting joint is prepared by brazing through processes such as acid pickling,weaving,indium plating,and welding,with a smooth surface and no exposed superconducting wires.And estimate the influence of superconducting joint resistance and joint size on magnetic flux jump,and finally characterize the prepared joint to verify its morphology.After verification,the prepared superconducting joint meets the design requirements.Based on the current attenuation method to test the resistance of superconducting joints,a resistance testing platform based on JASTEC 15 T backfield magnet is designed and assembled,including superconducting transformers,superconducting joint sample rings,current leads,Hall probes,and other accessories.The device has high testing accuracy and can replace joint samples without changing the low temperature of the back field magnet,reducing operating costs and shortening experimental cycles.A data acquisition system for high-precision superconducting joint resistance testing was designed using LabVIEW image programming software.Elaborated on the parameter characteristics of each collection hardware and its role in the collection system.Design temperature data acquisition programs and Hall voltage acquisition programs,and conduct temperature monitoring of magnet cooling and excitation experiments at low temperatures.After verification,the two programs designed in this project have good scalability,and can be applied to other low-temperature platforms with only a few changes in hardware settings,making it easy to operate and use. |
