磁悬浮系统中多芯复合Nb3Sn超导线磁通跳跃的可调性研究  

Tunable flux-jump characteristic of multifilamentary composite Nb3Sn superconducting wires in maglev systems

作　　者：董石泉 何安 刘伟 薛存 Dong Shi-Quan;He An;Liu Wei;Xue Cun(Department of Engineering Mechanics,College of Science,Chang’an University,Xi’an 710064,China;Western Superconducting Technologies Co.,Ltd.Xi’an 710014,China;Department of Engineering Mechanics,School of Mechanics,Civil Engineering and Architecture,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]长安大学理学院工程力学系,西安710064 [2]西部超导材料科技有限公司,西安710014 [3]西北工业大学力学与土木建筑学院工程力学系,西安710072

出　　处：《物理学报》2023年第1期284-295,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11972298);陕西省自然科学基础研究计划(批准号:2022JM-025,007234930030);中央高校基本科研业务费专项资金(批准号:300102121201);陕西省重点研发计划(批准号:0105679005)资助的课题。

摘　　要：超导磁悬浮列车在加速启动的过程中,载有恒定大电流的超导线圈处在变化的磁场中,这会导致超导线圈发生磁通跳跃,从而降低线圈的载流能力.并且磁通跳跃会产生大量热量而使超导线圈温度急剧升高,严重时会导致超导线圈失超,所以对磁通跳跃的研究具有非常重要的科学意义.Nb3Sn超导线是由多根微米级的超导芯丝、铜和环氧树脂形成的复合结构.本文通过约束每根芯丝的静电流为零的二维模型来分析三维绞扭效应,研究了超导线在交变磁场和恒定电流下的磁热不稳定性行为.通过分析交变磁场的幅值和频率对Nb3Sn超导线磁通跳跃的影响,发现当磁场幅值不变时,初次发生磁通跳跃的磁场阈值Bth随频率非单调变化.而当频率一定时,初次发生磁通跳跃的磁场阈值Bth随交变磁场幅值单调变化.此外,随着幅值的减小,发生磁通跳跃的频率区间先变大后变小,直到某个临界频率后超导线不再发生磁通跳跃.本文的研究结果能够为调控超导线的磁热不稳定性行为提供理论依据.The superconducting solenoid with constant large current is exposed to an alternating magnetic field during the acceleration of the superconducting maglev train,which will cause flux jump of the superconducting solenoid.It can reduce the current-carrying capacity of the solenoid,and generate a lot of heat and make the temperature of the superconducting solenoid rise sharply,which will make the whole superconducting coils quenched.Thus the research of flux jump has very important scientific significance.Nb3Sn superconducting wire is a composite structure composed of multiple superconducting filaments、copper and epoxy resin.In this paper,the magneto-thermal instability behavior of a three-dimensional superconducting wires under alternating magnetic fields and constant current is studied by using a two-dimensional model in which the net current of each filament is constrained to zero.By analyzing the effect of amplitude and frequency of alternating magnetic field on flux jump of a Nb3Sn superconducting wire,we find that when the magnetic field amplitude keeps unchanged,the magnetic field threshold of the initial flux jump changes non-monotonically with the frequency.While the frequency keeps unchanged,the threshold of the initial flux jump changes monotonously with the amplitude of the alternating magnetic field.In addition,with the decreasing applied field,the frequency range for flux jump first increases then decreases to certain critical frequency when the superconducting wire does not have flux jumps.The results of this paper can provide a theoretical basis for regulating the magneto-thermal instability of superconducting wires.

关 键 词：Nb3Sn多芯复合超导线 磁通跳跃 交变磁场 磁悬浮系统 

分 类 号：U266.4[机械工程—车辆工程]