HTS电流引线中接头电阻的研究和焊接工艺

针对Bi-2223/Ag-Au高温超导带材制造的二元HTS电流引线设计中不同材料之间连接的技术要求,设计了减小接头电阻的焊接工艺实验,包括焊接温度、焊料、搭接长度和焊锡层厚度对接头电阻的影响。着重分析了HTS电流引线中应用的三种接头的焊接工艺对焊接电阻的影响,并总结出在HTS电流引线中接头电阻的焊接工艺参数。     

飞秒激光照射金箔的传热机理研究

本文采用抛物线两步(PTS)模型和双曲线两步(HTS)模型模拟了超短脉冲激光(脉冲宽度小于100 fs)照射金箔的传热过程。本文将不同模型的模拟结果与破坏阀值的实验数据进行了比较,结果表明HTS模型更加符合实验结果。本文的数值研究为瞬态激光材料加工技术提供理论依据.     

HTS磁体性能实验研究

系统介绍 HTS实验磁体的液氮、液氦实验和固氮浸渍实验 ,获得 78.6～ 4 .2 K不同温度下磁体的伏～安特性曲线和 Ic～ T曲线 ,在很宽的范围内研究了 HTS实验磁体性能。     

浮力式低温液位计的设计原理及运行工况分析

全超导磁约束核聚变实验装置EAST的13对磁体电流引线全部采用高温超导(HTS)。为保证其安全运行,特为其液氮储槽设计制作了浮力式液位计。经过几轮物理实验,证明这种深冷液位计能较准确地监视HTS电流引线液氮储槽的液面,从而保证HTS电流引线的安全运行。文中介绍浮力式深冷液位计的设计原理及其运行工况。     

HTS块材与磁场间相互作用估算方法研究

HTS块材电磁机构日趋复杂,为了实现系统结构和电磁设计的优化需要建立一种简单可靠的方法来估算系统内部的相互作用.描述HTS磁学特性通常采用热激活磁通跳跃、磁通流动等系列模型,用其描述相互作用各有优缺点.为此,我们实验测试了HTS块材与永磁间相互作用随空间相对位置变化,并基于HTS完全抗磁性和临界态模型构造的B(H)曲线进行模拟仿真,通过与实验结果的比较,力求寻找一种方便可行、较为准确及可靠的HTS块材与磁场间相互作用估算方法.     

EAST降温实验中HTS电流引线的降温操作与自动控制

EAST装置的8对铜电流引线于2007年升级改造为HTS电流引线。基于改造后的冷却回路和降温操作经验,在低温DCS中设计并实现了HTS电流引线降温操作的自动控制,包括降温流程的顺序控制和自动安全监控,以及液位和温度等关键过程参数的自动控制回路。经过降温实验验证,以上自动控制策略完全满足HTS电流引线的降温要求。     

高温超导电力电缆开发及应用近况

文中主要介绍了主要工业化国家中的美国、德国、日本和我国在高温超导电力电缆研制和应用计划的一些最新进展,表明HTS电缆商业应用技术已经接近成熟。最后对我国HTS电缆的研究发展提出了建议     

高温超导块材在旋转场中的电磁响应

高温超导(HTS)块材在旋转系统中会受到旋转磁场的影响,为此我们建立了实验装置用以模拟和反映块材在旋转场中的电磁响应,并结合实验现象从理论上初步探讨了旋转磁场中HTS内部磁通渗透过程和能量损耗机理.     

HTS块材与磁场间相互作用估算方法研究

HTS块材电磁机构日趋复杂，为了实现系统结构和电磁设计的优化需要建立一种简单可靠的方法来估算系统内部的相互作用．描述HTS磁学特性通常采用热激活磁通跳跃、磁通流动等系列模型，用其描述相互作用各有优缺点．为此，我们实验测试了HTS块材与永磁间相互作用随空间相对位置变化．并基于HTS完全抗磁性和临界态模型构造的B（H）曲线进行模拟仿真，通过与实验结果的比较．力求寻找一种方便可行、较为准确及可靠的HTS块材与磁场间相互作用估算方法．     

Bi2223/Ag带HTS双饼线圈中的接头焊接

降低双饼线圈间的搭接电阻 ,可有效提高 HTS磁体的稳定性并降低制冷费用。文中在分析影响搭接电阻因素的基础上 ,对双饼线圈间的焊接工艺和接头性能进行了实验研究 ,结果表明所用焊接技术满足磁体稳定运行的要求     

Graded finite element simulation of thermal stress in inhomogeneous high-Tc superconductor

YBa₂Cu₃O_y is an orthotropic material with different material properties in a, b and c directions, such as Young’s modulus, coefficient of thermal expansion (CTE), and thermal conductivity. It is assumed that the material properties of inhomogeneous high temperature superconductor (HTS) vary with different height coordinate and temperature. A model is presented in this paper to calculate the thermal stress of inhomogeneous HTS when temperature decreases from ambient to operating conditions (cryogenic temperatures). By fitting a second order polynomial to the experimental data, value of the material properties of inhomogeneous HTS can be obtained. Then, through the proposed graded finite element method, the coupled thermo-mechanical equations were solved numerically. The numerical results show that the temperature profiles distribute the function of time after soaking. It is notable that the temperature profile reaches steady in a very short period of time, so the thermal stress suddenly increases to a very high level for a bulk superconductor. It is also shown that the closer to the sample internal region it is, the larger the heat fluxes are. Besides, the maximum tensile stresses, i.e. the peeling stresses, occur near bottom corner of inhomogeneous HTS. It is intended that the model presented in this paper could be useful to researchers who are interested in mechanical properties of inhomogeneous HTS.     

Peeling stress analysis for an inhomogeneous high-Tc superconductor with a discontinuous interface at the substrate

This paper presents an analysis of a superconductor–substrate system to calculate the peeling stress of a high temperature superconductor (HTS) when the temperature decreases from ambient to operating conditions (cryogenic temperatures). Firstly, the values for the material properties of the inhomogeneous high temperature superconductor (HTS) were obtained by fitting a second order polynomial to the experimental data. It is assumed that the material properties of the inhomogeneous HTS vary with varying height coordinate and temperature. Then, through the proposed graded finite element method, the coupled thermo-mechanical equations were solved numerically. The numerical results show that the thermal stress generated in the inhomogeneous HTS is larger on a SiTiO₃ substrate than on a MgO substrate. The maximum thermal stresses, i.e., the peeling stresses, occur near the bottom corner of the inhomogeneous HTS and may induce fracture behavior at the bi-material interface. The inhomogeneous HTS cools at a slower pace than the homogeneous HTS from the room temperature to the operating temperature. It is also shown that the magnitude of the peeling stress for a homogeneous HTS is larger than that for an inhomogeneous HTS. It is intended that the model presented here be useful to researchers who are interested in the mechanical properties of an inhomogeneous HTS.     

Influence of experimental methods on crossing in magnetic force–gap hysteresis curve of HTS maglev system

The crossing in magnetic levitation force–gap hysteresis curve of melt high-temperature superconductor (HTS) vs. NdFeB permanent magnet (PM) was experimentally studied. One HTS bulk and PM was used in the experiments. Four experimental methods were employed combining of high/low speed of movement of PM with/without heat insulation materials (HIM) enclosed respectively. Experimental results show that crossing of the levitation force–gap curve is related to experimental methods. A crossing occurs in the magnetic force–gap curve while the PM moves approaching to and departing from the sample with high or low speed of movement without HIM enclosed. When the PM is enclosed with HIM during the measurement procedures, there is no crossing in the force–gap curve no matter high speed or low speed of movement of the PM. It was found experimentally that, with the increase of the moving speed of the PM, the maximum magnitude of levitation force of the HTS increases also. The results are interpreted based on Maxwell theories and flux flow-creep models of HTS.     

八信道高温超导多路器的实验研究

文中首先分析八信道高温超导多路器设计的方案,以及实现八信道高温超导多路器的技术;给出了用MgO基片为衬底,YBCO超导膜制备的高温超导滤波器设计仿真曲线及实际测试曲线;并对多路器所用制冷器的制冷量进行了计算;最后给出八信道高温超导多路器的实际测试曲线。     

场冷条件下超导块材的吸引力与排斥力

基于K im临界态模型,通过考虑超导块材内部屏蔽电流的穿透历史过程,其计算了不同场冷条件下高温超导悬浮系统的悬浮力。其计算结果与实验结果吻合很好。结果显示:超导块材的最大吸引力随场冷高度的升高呈指数关系减小;达到最大吸引力的悬浮高度随场冷高度的增加近似呈线性关系增长。最大排斥力随场冷高度的变化曲线存在临界值:当场冷高度小于临界值时,最大排斥力呈线性关系增加;反之,最大排斥力呈指数关系增长。悬浮力与场冷高度的这些变化规律可以用超导块材内部屏蔽电流的穿透情况进行很好地解释,为超导块材的实际工业应用提供了重要的理论依据。     

高温超导强电应用研究进展与展望

评述了目前高温超导材料强电应用研究的进展,着重介绍了故障电流限制器(FCL)、输电电缆、变压器等热点项目,以及美国在军事方面的应用动向,对高温超导强电应用前景进行了展望。     

时变外磁场中高温超导块材导向力性能的数值模拟

基于Bean临界态模型,针对目前的高温超导磁悬浮车系统,提出了一种模拟计算方法,该方法可计算在时变外磁场中块材导向力的衰减变化情况。通过对时变外磁场中块材温度、俘获磁通以及导向力等参数变化情况的实验结果和计算结果的对比,证实了该模拟计算方法的有效性。该模拟计算方法可用于定性研究高温超导块材的导向力性能在时变外磁场作用下的变化情况,为高温超导磁悬浮车的研究和工程实践提供了较为重要的科学依据。     

Effect of the twisting chirality configuration on the electromechanical behavior of multilayer superconducting tapes

Seeking a geometry that can withstand greater transverse loads based on the electromechanical material properties of high-temperature superconducting (HTS) tape is an effective way of improving the transport performance of HTS cables. The cabling method requires the determination of the optimum twist angle of the HTS tape for withstanding transverse loads. This paper investigates the critical current characteristics of HTS tapes under combined deformation. The limit range of the twist angle under the combined deformation is measured and the optimum twist angle of the HTS tape is determined. The results show that the twisting chirality configuration obviously affects the bending strength of the HTS tape. In the elastic range, increasing the pre-twist angle increases the bending strength of the HTS tape, thereby improving the transport performance. In addition, a numerical model is built to further investigate the effect of the twisting chirality configuration on the electromechanical properties of the HTS tape, and the experimental results are explained. The experimental and simulation results generally agree well, and calculations show that there is always a sharp change in stress at the interface of different materials. These findings explain the mechanism of the effect of the twisting chirality configuration on the mechanical behavior and critical current of the HTS tape. They also provide a reference for cabling methodologies for the HTS cable configuration.