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1.
测量了高温超导导线Bi-2223/Ag的临界电流值与外加磁场的依赖性关系.实验结果表明:超导线材的临界电流不仅与磁场大小有关,而且还与外磁场的方向有关.外磁场越大,临界电流值越小;Bi-2223/Ag呈扁带状,临界电流对磁场的依赖性呈现各向异性.该实验与高温超导材料临界温度测量实验结合为高温超导电性能综合测试实验,为学生自主研究提供了拓展空间.  相似文献   

2.
为了研究磁场、温度对Bi-2223/Ag带材超导性能的影响,建立了一套测量带材临界电流的实验装置,该装置能够提供稳定的背景磁场,控温精度最高可达±20m K,在零场、控温(77.3K)条件下样品的临界电流测量值与带材给定参数基本吻合,表明该装置测量精度满足要求;文中将高温超导带材放在特制控温罩中,使用He气冷技术和温控系统调节样品温度(4.2—80K),测量了在0—12T背场下高温超导带材的临界电流,并系统地分析了Bi-2223/Ag带材临界电流对温度和磁场的依赖关系。  相似文献   

3.
Bi2223/Ag带小型高温超导实验磁体设计   总被引:3,自引:0,他引:3  
Bi2223/Ag带材的强各向异性决定了其临界电流对垂直于带材表面的磁场非常敏感,这是该带材在高温超导磁体等强电应用方面的不利因素。我们从减小磁体最大径向场BRmax对磁体运行电流的影响、充分利用超导材料的原则出发,讨论了高温超导磁体的设计方法。在小型Bi2223/Ag实验磁体的设计中,根据对径向磁场的计算、分析,确定了磁体的工作点。  相似文献   

4.
Bi-2223/AgAu 高温超导带材因为较低的热导率和较高的载流性能, 被认为是制备高温超导电流引线的最佳材料之一. 这篇文章简单介绍了高温超导电流引线的工作特点和不同包套 Bi-2223 带材的热导率, 在此基础上详细介绍了目前 Bi-2223/AgAu 带材和高温超导电流引线国内外研究进展, 最后展望了 Bi-2223 带材的发展趋势.  相似文献   

5.
本文利用Bi-2223/Ag高温超导带材与抗拉强度σb为700MPa的铜带进行组合,带材宽度面间采用低熔点的Sn-Ag-Cu无铅焊料进行连接,制备了C-SC-C型、SC-C-SC型(C代表铜带,SC代表高温超导带)等四种层状复合结构.研究和考察了四种结构样品在室温下的拉伸性能和弯曲性能,以及电性能等.测试结果表明:与高温超导带材相比,复合后结构的拉伸性能得到了提高;复合结构中采用两根高温超导带材后,提高了传输电流的能力.研究结果为Bi-2223/Ag高温超导带材的实际应用以及新应用结构的设计提供了参考数据和实验依据.  相似文献   

6.
Bi-2223带材有阻焊接接头电阻特性的研究   总被引:3,自引:0,他引:3  
本文针对Bi-2223/Ag带材接头有阻焊接展开研究,考虑大电流时超导I~V特性非线性影响,建立焊接接头电阻特性的有限元计算模型,总结出不同搭接距离和焊锡层厚度对接头电阻的影响规律,并着重分析了接头电阻对临界电流的影响,最终通过实验验证了理论分析得到的一些基本规律.为降低Bi-2223/Ag带材接头电阻对高温超导磁体运行时的不利影响,实际焊接时搭接距离应保证在7~10cm以上.  相似文献   

7.
Bi-2223/Ag是一种很有前景的高温超导带材,交流损耗是高温超导在大规模电力应用方面的瓶颈,如何降低Bi-2223/Ag中的交流损耗是人们一直关注的问题。带材超导部分的横截面形状对交流损耗有很大的影响,前人曾通过双轴轧制等工艺制造矩形截面的带材,以降低其交流损耗;另有人在单芯带材中得到了环状结构,从中发现可降低交流损耗。本论文尝试利用抽换芯工艺制造多芯环状截面的Bi-2223/Ag高温超导带材,以期降低带材的交流损耗。论文中,通过解析方法计算了临界态模型下,临界电流密度在径向上分布不均匀的超导体的交流损耗特性,并得到结论:带材的外围临界电流密度越高,交流损耗性能越好。  相似文献   

8.
对Bi-2223/Ag高温超导带材的失超传播特性进行了研究。测量了Bi-2223/Ag带材在有绝缘材料包裹和液氮浸泡环境下的电压变化曲线,同时利用一维热流方程模型,模拟出超导体失超传播过程中由超导态过渡到正常态的温度变化行为,同时还对传输电流和触发能量对失超传播速度的影响进行了实验研究。这些工作对高温超导磁体及电力系统的应用有着重要的参考价值。  相似文献   

9.
采用测量多个电压节点顺序失超的方式,测量了在液氮浸泡和有包裹材料情况下不锈钢加强Bi-2223/Ag和YBCO涂层导体高温超导带材样品的失超传播速率。根据实验结果,Bi-2223/Ag高温超导带的失超传播速率约为2 cm/s,YBCO带材的失超传播速率约为0.4 cm/s,均远远低于低温超导材料的相应数值。对这一现象的原因进行了简要分析,并根据高温超导带材的这一特点,提出了在高温超导电力应用中需特别注意的问题。  相似文献   

10.
Bi—2223带材在拉伸应力下的临界电流   总被引:1,自引:1,他引:0  
研究了不锈钢加强的Bi-2223/Ag高温超导带材在不同的拉伸应力下临界电流的变化情况。采用改造后的拉伸设备,在温度77K下对超导带材施加拉伸应力的同时,利用四引线法测量带材的临界电流,得到了超导带材的应力—应变曲线以及临界电流—应变曲线。利用理论公式计算了应力对超导带材临界电流的影响,与实验结果进行对比,并对两者的差别进行了分析。  相似文献   

11.
The critical current of high-temperature superconductor (HTS) tapes depends on temperature, magnetic field, and flux angle against the tape. Analyzing the performance of an HTS coil relies on the critical current equation, which has these dependencies. To date, the critical current equation has been obtained by fitting the measured data. However, this fitting method requires the time-consuming and laborious work of measuring the tapes. In this study, based on a new transition concept in applying a magnetic field, we show how to obtain the critical current equation, while keeping the temperature constant. From the wave function of the Cooper pair which distributes along a magnetic flux quantum, a wave function at the transition state is obtained; this yields the wave functions with perpendicular and parallel magnetic components against the tape. Combining these wave functions yields the conclusive critical current density equation. To confirm the accuracy of this equation, used Bi-2223/Ag tapes, it was compared with the measured critical current under various magnetic fields and flux angles; it was found that they agree well. The parameters of this equation can be obtained by measuring the perpendicular/parallel critical magnetic field component. This equation does not require fitting the measured data, therefore, it can be employed with any Bi-2223/Ag tape.  相似文献   

12.
The use of Bi-2223 high temperature superconducting (HTS) tape as a material for gradient coils in MRI is evaluated in this paper. Bi-2223 tapes have a very high critical current and a very low power loss. A HTS tape gradient coil is expected to provide much higher gradient strength and generate much lower heating than a copper coil. Measurements of the AC power loss of Bi-2223 tapes at typical operating frequencies for gradient coils are presented. The degradation of the critical current and its effect on the increase of AC power loss is analyzed. Practical technical issues such as resistance, gradient strength and mechanical performance are also discussed. A prototype Bi-2223 HTS tape gradient coil is evaluated to verify the concept.  相似文献   

13.
Some results of AC loss measurements are presented for 19, 61, 127-filamentary Bi-2223/Ag tapes prepared by the ‘powder-in-tube' method. All measurements have been made at T=77 K under sinusoidal transport current with frequency in the range of 30–600 Hz and the current amplitude up to 30 A. The measurements have been carried out both in self field conditions and at the external magnetic field applied to the tape at the different angles. The dependencies of the AC losses on current amplitude and frequency have been obtained. It is found that for all tapes the current amplitude dependencies of the AC losses show good agreement with the Norris prediction for an elliptical or strip geometry. The AC loss dependencies on frequency were linear. The measurements of AC losses in external magnetic field show that the change of AC losses is only through the change of the critical current. So the transport AC losses in the tapes are the ‘saturation losses' that is they are different from classic hysteresis losses.  相似文献   

14.
高温超导带材在磁场中传输交变电流时,将受到电磁力的作用而产生机械振动,振动对带材的交流损耗将产生影响.本文讨论了振动情况下交流损耗的测量方法,在平行于带面的直流磁场下,测量了Bi-2223/Ag高温超导带材在不同振动情况下的交流损耗.结果显示:当传输电流频率偏离样品的共振频率时,振动对带材的交流损耗影响不大;只有当电流频率在共振频率附近时,样品产生剧烈振动,交流损耗才有明显的增加;另外,带材振动时的交流损耗随频率变化曲线的斜率比不振动时略有增加.  相似文献   

15.
The effect of current sweep reversal on the temporal drift in magnetic field intensity for a Bi-2223 solenoid was investigated by experiment and using numerical simulation. Current sweep reversal, by as small as 1% of the peak current, was found to stabilize the drift in magnetic field intensity for a Bi-2223 tape solenoid. The field drift was due to flux creep in the Bi-2223 tape and the current sweep reversal formed a barrier for flux entrance at the upper and lower surface of the conductor, preventing flux creep. With a current reversal of several% of the peak current, the barrier formation extended over half of the solenoid and the magnetic field intensity became constant with time. The current sweep reversal technique should prove useful to stabilize an ultra-high field low/high-temperature superconducting nuclear magnetic resonance magnet operated at frequencies (field intensities) beyond 1 GHz (23.5 T).  相似文献   

16.
ITER电流引线高温超导叠制作工艺及性能测试   总被引:2,自引:0,他引:2  
ITER高温超导电流引线载流能力最大要达到68 kA,一根电流引线共需要1000多根银金基Bi-2223高温超导带并联.这些高温超导带分成90叠,每叠由12层带组成.银金基Bi-2223带价格是普通银基Bi系带的4~5倍,而目前欧洲超导公司提供的超导叠的报价几乎是其带价格加倍,所以开发超导叠的制作工艺是非常有价值的.本文详细的介绍了超导叠的真空钎焊制作工艺,并进行了77 K下超导带的接头电阻测试和77 K自场下的临界电流测试,以及模拟在实际运行温度65~5 K条件下高温超导叠的载流能力测试和接头电阻的测试.测试结果证明了此工艺的可行性.  相似文献   

17.
A comparative study on the critical current performance of Bi-2223/Ag and YBCO coated conductor wires in low magnetic fields at liquid nitrogen temperature was carried out in this work. Five commercial high temperature superconductor wires from different manufacturers were collected. Their critical currents were measured in magnetic fields, ranging from 0 to 0.4 T. On contrary to the common conception, the Bi-2223/Ag samples had better performance than YBCO coated conductor samples in the magnetic fields parallel to the wide surface of superconducting wires within the experimental scope. We also found similar results by collecting the concerned datum from the published literatures to confirm our measurement results. At the present stage, this fact made that the Bi-2223/Ag wires might be the preferred choice for the applications with mainly low parallel fields involved, unless other considerations were prioritized.  相似文献   

18.
主要研究了铁磁材料对Bi-2223带材的临界电流的影响。通过计算铁磁材料在不同布局下对带材磁场分布的影响,进行了相应的临界电流测试实验。分析表明,将铁磁材料垂直放在带材边缘能有效地提高带材的临界电流。  相似文献   

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