Research On Finite Element Analysis Of Complex High Temperature Superconducting Structure

High temperature superconducting?HTS?complex structure like Twist,Stack,cable in conduit conductor?CICC?,conductor on round core?CORC?,Twisted Stack,Roebel have many advantages over single HTS materials.They have larger current carrying capacity,higher magnetic field and better flexibility.Therefore,they are widely used in HTS large devices.Besides,as the fabrication technological bottlenecks of kilometer-long HTS tape and the layered structure of 2^nd HTS tapes,the research of joint fabrication technology becomes a hot topic.In order to explore the electromagnetic properties of HTS complex structure cable and joint,this paper research it based on numerical methods.With the rapid developing of commercial finite element analysis?FEA?software,numerical research on simple HTS materials is quite mature.The commonly used numerical methods are finite element method?FEM?,field-circuit coupling method and power system analysis method.On the basis of existing model,this paper uses financial software COMSOL Multiphysics to set up the three-dimensional?3D?models.Firstly,a single 2^nd HTS tape model is set up based on H-formulation.This model is validated by comparing the 3D simulation results with two-dimension?2D?simulation results and theoretical results.On basis of this,a stack model with three tapes and a silver diffusion bridge-type HTS joint model are set up to explore the relationship between the fabrication process and parameters like joint resistance,silver usage,current distribution.This will provide guidance to the fabrication of HTS joints.Nowadays,CORC structure has broad application prospects due to its good performance in high magnetic field environment.This paper set up CORC model based on field-circuit coupling method.By this model,the influence of CORC parameters on its critical current under self-field is researched.The parameters include the start phase,the number of tapes per layer,the number of layers,the twist pitch and so on.The results of bridge-type HTS joint model shows that the joint resistance is not affected by the thickness of superconducting layer,but proportional to silver layer.Moreover,the joint resistance is inversely proportional to the contact area.However,the influence on the joint resistance of contact length is larger than contact width.The results of CORC model shows that the critical current of a single tape in CORC is not affected by the start phase of the tapes and the number of tapes per layer.Moreover,the critical current of a single tape is inversely proportional to the number of layers and the twist pitch.However,the influence of number of layers is larger.