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低温/高温复合超导体的热稳定性的数值模拟研究 总被引:2,自引:0,他引:2
本文提出了一种高温超导体与低温超导体直接复合成混杂结构的复合超导体的导体模型.针对NbTi/Bi2223复合超导体的热稳定性进行了初步的理论模拟研究,结果表明低温/高温复合超导体的最小失超能远大于低温超导体,失超传播速度介于纯低温超导体和高温超导体之间,对于超导磁体的热稳定和保护具有重要参考价值. 相似文献
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低温/高温复合超导体是将高温超导体部分取代复合实用低温超导体中的金属稳定材料或两者直接复合成一体,这种复合超导体具有稳定性高,工程电流密度大等优点.本文对NbTi/Bi2223高温复合超导体中的电流分布进行了理论研究,并得出液氦温度下,如果复合超导导体中,低温超导体和高温超导体具有相同的临界电流,超导体正常运行时低温超导体中的电流大于高温超导体中的电流,两者之比随运行电流的升高而降低. 相似文献
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本文基于超导体幂指数模型对低温超导体和高温超导体的分流温度分别作了数值计算,计算结果与现有的分流温度估算公式结果符合的很好.本文还讨论了幂指数模型中不同n值对低温/高温复合超导体分流温度的影响,并对复合超导体分流温度做了数值计算,结果显示在相同传输电流下,低温/高温复合超导体的分流温度比传统低温超导体的分流温度高3.2K以上,这表明这种复合超导体较传统低温超导体具有更好的稳定性. 相似文献
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铁基超导体中普遍存在着反铁磁、超导和向列相,因此研究向列相的性质及其与反铁磁、超导的关系对于理解铁基超导体的低能物理及高温超导电性具有非常重要的作用.所谓向列相是指电子态自发破缺了晶格的面内四重旋转对称性而形成的有序态,从而导致样品的某些物理性质出现了两重的各向异性.我们通过自主研发的单轴压强装置,可以在低温下原位改变压强,测量电阻的变化,从而得到向列极化率.本文介绍了我们利用该装置在最近几年研究铁基超导体的向列相和向列涨落所取得的一些成果,包括详细研究了BaFe_(2-x)Ni_xAs_2体系中的向列量子临界点及其量子临界涨落,并提出了基于向列涨落强弱调节的铁基超导体统一相图.这些结果表明,向列相及其涨落与反铁磁和超导均有很强的耦合,对于理解铁基超导体中磁性和超导电性非常关键. 相似文献
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基于工程化高温超导带材的内冷型复合超导体电磁特性受磁场各向异性影响较大,采用有限元方法分析了内冷型复合超导体的电磁特性。利用COMSOL Multiphysics建立了基于商品化高温超导带材的金属封装内冷型高温复合导体的有限元计算模型,并对其进行电磁仿真分析,得到了内冷型复合超导体的磁场分布,应用高温超导材料在磁场下的Jc-B曲线关系,获得内冷型复合导体在77K液氮温区下临界电流受磁场影响的变化规律。采用电场强度与电流密度进行面积分的方法,计算得到了不同频率、不同通流下内冷型复合导体的交流损耗情况,计算表明,相同频率下交流损耗随激励电流的增大而增大,相同激励电流条件下交流损耗与通流频率成正比关系。 相似文献
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较之高温制备,低温活化烧结技术可有效避免MgB2超导块体制备中的一些问题,如Mg易挥发、高温MgB2晶粒长大、结晶度高等问题.为进一步提高超导块体的载流能力,J Shimoyama等采用金属Ag掺杂并在550℃烧结72h后获得了高性能的MgB2超导体,使得金属Ag成为低温活化烧结的有效组元.然而,对金属Ag低温活化烧结MgB2超导块体的成相机理尚缺乏系统的分析和理解.本文系统研究了金属Ag掺杂MgB2超导块体的成相动力学过程,发展了金属Ag掺杂低温活化快速制备技术,结合液相活化烧结理论阐述了金属Ag掺杂MgB2块体的低温活化烧结机理. 相似文献
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我们在Y-Ba-Cu-O系中得到零电阻温度Tcf为94.1K,中点转变温度Tc为95K,起始转变温度Tci为100K,转变宽度△Tc为1K的超导体。低温X光衍射结构分析结果表明,多相超导体在低温区(123—173K)有相变。因此,我们认为Y-Ba-Cu-O系中多相超导体的高Tet是低温相变引起的,并不完全是超导转变点。在该系氧化物中以Cr取代1/3的Cu,仍然得到Tcf=82.8K、Tc=83.5K、Tci=92K、△Tc=1K的超导体。 相似文献
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简要地介绍了磁约束托卡马克装置中用超导磁体代替常规磁体的发展方向 ;叙述了可能用在聚变中的两类高温超导材料 ,并讨论了托卡马克磁体对高温超导体的特殊要求 ;描述了高温超导体的聚变应用进展 ;介绍了高温超导电流引线以及 A- SSTR2反应堆高温超导环场 (TF)线圈的概念设计 相似文献
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M. S. Novikov D. P. Ivanov S. I. Novikov S. A. Shuvaev 《Physics of Atomic Nuclei》2015,78(10):1148-1154
Application of current-carrying elements (CCEs) made of second-generation high-temperature superconductor (2G HTS) in magnet systems of a fusion neutron source (FNS) and other fusion devices will allow their magnetic field and thermodynamic stability to be increased substantially in comparison with those of low-temperature superconductor (LTS) magnets. For a toroidal magnet of the FNS, a design of a helical (partially transposed) CCE made of 2G HTS is under development with forced-flow cooling by helium gas, a current of 20–30 kA, an operating temperature of 10–20 K, and a magnetic field on the winding of 12–15 T (prospectively ~20 T). Short-sized samples of the helical flexible heavy-current CCE are being fabricated and investigated; a pilot-line unit for production of long-sized CCE pieces is under construction. The applied fabrication technique allows the CCE to be produced which combines a high operating current, thermal and mechanical stability, manufacturability, and low losses in the alternating modes. The possibility of fabricating the CCE with the outer dimensions and values of the operating parameter required for the FNS (and with a significant margin) using already available serial 2G HTS tapes is substantiated. The maximum field of toroidal magnets with CCEs made of 2G HTS will be limited only by mechanical properties of the magnet’s casing and structure, while the thermal stability will be approximately two orders of magnitude higher than that of toroidal magnets with LTS-based CCEs. The helical CCE made of 2G HTS is very promising for fusion and hybrid electric power plants, and its design and technologies of production, as well as the prototype coils made of it for the FNS and other tokamaks, are worth developing now. 相似文献
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A. M. Petrzhik G. A. Ovsyannikov A. V. Shadrin K. I. Konstantinyan A. V. Zaitsev V. V. Demidov Yu. V. Kislinskii 《Journal of Experimental and Theoretical Physics》2011,112(6):1042-1050
Hybrid herostructures comprising an YBa2Cu3O
x
(YBCO) high-temperature superconductor (HTS) layer and Nb/Au low-temperature superconductor (LTS) bilayer (with critical
HTS and LTS temperatures T
c and T′c, respectively), separated by a thin (d
M = 5–20 nm) interlayer of LaMnO3, La0.7Ca0.3MnO3, or La0.7Sr0.3MnO3 manganite have been studied. The electric resistance and magnetic properties of individual (evaporated directly onto the
substrate) manganite films and related hybrid herostructures have been measured. Based on quasi-classical equations, analytical
expressions for the conductivity of herostructures at T ≤ T′c are obtained in the case of a low-transparency superconductor/manganite interface. It is established that the conductivity
of heterostructures is determined by the proximity effect (related to the penetration of a condensate wavefunction from the
Nb/Au bilayer to manganite) and depends strongly on interface transparency. At low temperatures (T ≪ T
c′), the conductivity peaks are found at voltages determined by the exchange field of the manganite interlayer. At T
c′ < T < T
c, conductivity features at nearly zero bias voltages are observed, which are related to the superconductivity of the YBCO
electrode. 相似文献
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Angular dependence of vertical force and torque when magnetic dipole moves vertically above flat high-temperature superconductor
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The interaction between a permanent magnet (PM) assumed as a magnetic dipole and a flat high-temperature superconductor (HTS) is calculated by the advanced frozen-image model. When the dipole vertically moves above the semi-infinite HTS, the general analytical expression of vertical force and that of torque are obtained for an arbitrary angle between the magnetization direction of the PM and the c axis of the HTS. The variations of the force and torque are analyzed for angle and vertical movements in both zero-field cooling (ZFC) condition and field cooling (FC) condition. It is found that the maximum vertical repulsive or attractive force has the positive or negative cosine relation with the angle. However, the maximum torque has the positive or negative sine relation. From the viewpoint of the rotational equilibrium, the orientation of the magnetic dipole with zero angle is deemed to be an unstable equilibrium point in ZFC, but the same orientation is considered as a stable equilibrium point in FC. In addition, both of the variation cycles of the maximum force and torque with the angle are π. 相似文献
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