The Study Of AC Loss Of High Temperature Superconducting Circular Helical Conductor

AC losses have an important impact on the operational stability and manufacturing cost of superconducting devices.The problem of AC losses in superconductors has been a hot issue for researchers in the field of superconductivity,therefore,the study of AC losses in superconductors is of great significance to promote the practical application of superconductors.As an important means of studying AC losses in superconductors,the results of simulation can provide valuable reference for the design of superconducting devices.After continuous and in-depth research by researchers,a variety of simulation methods for analyzing AC losses in superconductors have been proposed,and the combination of these simulation methods and experiments has strongly promoted the development of superconducting technology.For high-temperature superconducting conductors,most of the research objects are in the form of straight structures,however,for large magnet coils such as nuclear fusion,the basic structure is a circular structure,for which the relevant research is still in its initial stage.For this reason,this paper investigates the AC loss characteristics of circular helical structure conductors by means of three-dimensional(3D)simulation.In this case,this paper firstly analyses the advantages and disadvantages of two finite element simulation methods from the perspective of simulation methods for 3D modelling;then the AC loss characteristics of single high temperature superconducting strips and single spiral high temperature superconducting strips are investigated through experiments and simulations;finally,based on the previous work,the AC loss characteristics of high temperature superconducting tape with a circular helical structure are investigated.The details are as follows:1.For the H and T-A methods,which are commonly used to analyze the AC loss problem of superconductors,three different configurations of AC loss models,namely H(1),T-A(1+1)and T-A(1+2),are investigated according to the configurations of the H and T-A methods in3 D simulation modelling.The number of meshes in all simulation models was controlled to ensure scientific accuracy and rigor.The final results show that the number of degrees of freedom in the T-A(1+1)configuration is lower and the computation time is shorter,while the computational accuracy of H(1)and T-A(1+2)is better than that of T-A(1+1),but the same accuracy can be achieved by mesh refinement,therefore,all 3D simulation models in this paper use the T-A(1+1)configuration..2.The AC loss characteristics of single high-temperature superconducting tape was investigated by experiments and simulations.The experimental measured values and simulated calculated values of the transmission loss of single high-temperature superconducting tape was compared,and the results showed that the 3D T-A method is very reliable;immediately afterwards,experiments and three-dimensional simulations of the transmission loss of helical tapes with four different winding angles were carried out,which further showed that the 3D T-A method is suitable for studying the AC loss characteristics,while the magnetization losses of both single high-temperature superconducting tape and single spiral-structured high-temperature superconducting tape are investigated and analyzed by the 3D T-A method.3.Based on the previous research work,the 3D T-A method is applied to the AC loss characteristics analysis of high-temperature superconducting tape with circular helical structure,and the AC loss characteristics of different ring radius,skeleton radius and winding turns are investigated for the circular helical structure,in addition to the AC loss characteristics of two layers of tapes with different winding directions,and the final results show that when the single-layer winding,the ring radius and skeleton radius increases gradually,the transport loss of the tape also increases,while when the number of winding turns increases,the transport loss of the tape decreases;when the circular radius increases gradually,the magnetization loss of the tape also increases,while when the skeleton radius and the number of winding turns increase,the magnetization loss of the tape decreases;for the two-layer winding case,the transport loss of the tape is smaller when the tape is wound in the reverse direction than in the same direction;as in the single-layer As in the case of single-layer,the transport loss of the tape increases as the radius of the circle and the radius of the skeleton increase,while the transport loss of the tape decreases as the number of winding turns increases;unlike the transport loss,the magnetization loss of the tape is smaller when the tape is wound in the same direction than when it is wound in the opposite direction;in addition,the magnetization loss of the tape increases as the radius of the circle increases,while the magnetization loss of the tape decreases as the number of winding turns increases The magnetization loss of the tape increases when the radius of the ring is increased,but decreases when the number of turns is increased;the magnetization loss of the tape hardly changes when the radius of the skeleton is changed.