ITER校正场线圈盒真空电子束焊接分析

Analysis for the vacuum electron beam welding of ITER correction coils case

校正场线圈是ITER大型超导磁体系统的重要组成部分,在线圈盒焊接过程中,若线圈盒内表面与对地绝缘接触部分的温度过高,将影响校正场线圈的超导绝缘性能。文中应用有限元焊接模拟软件SYSWELD对线圈盒的电子束焊接过程进行了数值模拟,利用双椭球热源与3D高斯热源的组合热源模拟真空电子束焊独有的"钉形"热源,得到了与实际较为相符的熔池形貌;确定了接触点上的温度分布,并分析其对校正场线圈的影响;同时,对比了不同线圈盒结构的温度场分布,从而得到能够保护对地绝缘的合理肩部尺寸。

Correction Coils(CC) are important components of ITER superconducting systems.During the welding procedure of the coil case,the high temperature in the interface of the coil case's interface and the ground insulation would affect the insulation performance of the correction coils.A simulation of the vacuum electron beam welding(VEBW) of the coil case was carried out by the use of the finite element analysis software SYSWELD for welding simulation.A composite heat source composed of double ellipsoid heat source and 3D conical Gaussian heat source was applied to simulate the working of EBW.It could be seen that there was a good consistency between the numerical results and the experimental results.The temperature of the nodes in the interface was obtained and the affect to the correction coils was analyzed.A comparison of temperature field among different structures of the coil cases was also made to get what the shoulder width contributes to the welding temperature field and the super conductor and an appropriate width was obtained.