| Chinese fusion engineering testing reactor(CFETR),is a tokamak type magnetic confinement fusion device,which aims to obtain new energy sources through controllable thermonuclear fusion reaction to solve the increasingly serious energy crisis.The central solenoid(CS)is the key coil in the superconducting magnet of CFETR.Due to its maximum field is required to be 12t,the two coils are winding by Nb3Sn superconductor because it can form a higher critical magnetic field.Nb3Sn coil have superconductivity by heat treatment process,and heat treatment process can eliminate the residual stress in the process of winding,so the research on heat treatment process of Nb3Sn superconducting coil is of great significance.A new method of atmosphere protection for large CICC coil is proposed,and the heat treatment process design of CFETR CSMC Nb3Sn coil is completed,and the contents and technical requirements of each process step are improved.According to the process and technical requirements of the heat treatment process,a set of corresponding heat treatment system and equipment is designed to verify the feasibility and scientificity of the process.According to the coil size and heat treatment requirements,the parameters of the heat treatment system and equipment are calculated,the design model of the equipment is determined,and the heat treatment system is built.Complete the overall commissioning of CFETR CSMC Nb3Sn coil heat treatment system,and it main purpose is to verify whether the heat treatment system can meet the requirements of heat treatment.The commissioning contents include:verifying whether the power and accuracy of the heating system meet the requirements;verifying whether the temperature uniformity of all parts of the coil of the same volume meets the requirements;verifying whether the argon protection protects the super conductor and armor It is not oxidized;it is preliminarily verified whether the short sample coil can meet the final assembly requirements of the coil manufacturing process under the control of the fixture.Beginning the two verification experiment of the model coil to improve and perfect the heat treatment system and equipment.Analyzed the input parameters of power and Argon in the process,and researched the precise control of furnace temperature.In the two experiments,analyzed the temperature curves and temperature uniformity of each position on the coil by the hot air blower on or off during the heat treatment.The results show that the temperature in the furnace can be precisely controlled by adjusting the input parameters of the heating power and the hot air blower is on or off.Analyzed the composition of the superconducting sample surface and the impurities in the exhaust gas,the scientific and reliability of argon protection is evaluated.By measuring the critical current and n value of the superconducting strand sample,the reliability of the heating system is verified.Through the measured the coil contour,the feasibility of coil clamping scheme is evaluated,and heat treatment process is the great role in the manufacturing process of Nb3Sn coil.According to the evaluation results of the model coil,adjust the heat treatment process,improve the input parameters of the heat treatment system,and achieve the conditions of the real coil heat treatment process.Complete the preliminary design and experimental verification process,formulate detailed Nb3Sn coil heat treatment process specification,carry out real coil heat treatment,conduct heat treatment in strict accordance with the process flow in the process specification,input the parameters in accordance with the technical requirements in the specification during the heat treatment process,compare the feedback parameters with the requirements after the heat treatment,and evaluate the real NbsSn coil heat place Whether the results of the processing meet the expectations. |
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