Mathematical model of voltage–current characteristics of Bi(2223)/Ag magnets under an external magnetic field
Mathematical model of voltage–current characteristics of Bi(2223)/Ag magnets under an external magnetic field
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Bi(2223)/Ag磁体在外磁场作用下电压-电流特性的数学模型
DOI：
10.1088/0953-2048/15/11/305
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
P. Kováč
中科院分区：
文献类型：
--
作者：
J. Pitel;A. Korpela;J. Lehtonen;P. Kováč
我们已经开发了一个数学模型，使我们能够预测的电压-电流V（I）特性的螺线管高温超导（HTS）磁体受到平行于磁体轴的外部磁场。该模型考虑了Bi（2223）Ag超导带材在20 K时临界电流-磁场（Ic（B））特性和n值的各向异性。根据电场与工作电流和临界电流之比之间的幂律，通过对各个匝的贡献进行积分来计算磁体端子上的电压。在给定的工作电流和外磁场值下，通过Ic（B）特性的两个适当点之间的简单线性插值来获得每匝的临界电流，Ic（B）特性对应于合成磁通密度矢量与宽带面之间的角度α。实际上，该模型适用于任何外磁场值和方向，并且仅受作为工作电流的函数的电场幂律的有效性的限制。由22个饼形线圈组成的模型磁体的各个匝的电场已被分析为不同的操作电流值和外部磁场。还分析了单个饼形线圈上的电压分布和磁体端子之间的总电压。最后，研究了不同工作电流下外磁场对磁体V（I）特性的影响。我们报告一个新的和相当意想不到的行为的高温超导磁体在不同的操作条件下，与理论解释。
We have developed a mathematical model, which enables us to predict the voltage–current V(I) characteristics of a solenoidal high-temperature superconductor (HTS) magnet subjected to an external magnetic field parallel to the magnet axis. The model takes into account the anisotropy in the critical current–magnetic field (Ic(B)) characteristic and the n-value of Bi(2223)Ag multifilamentary tape at 20 K. From the power law between the electric field and the ratio of the operating and critical currents, the voltage on the magnet terminals is calculated by integrating the contributions of individual turns. The critical current of each turn, at given values of operating current and external magnetic field, is obtained by simple linear interpolation between the two suitable points of the Ic(B) characteristic, which corresponds to the angle α between the vector of the resulting magnetic flux density and the broad tape face. In fact, the model is valid for any value and orientation of external magnetic field, and is only limited by the validity of the electric field power law as a function of operating current. Electric fields of individual turns of the model magnet, which consists of 22 pancake coils, have been analysed for different values of operating current and external magnetic field. The voltage distribution on individual pancake coils and the overall voltage between the magnet terminals have also been analysed. Finally, the influence of external magnetic field on the V(I) characteristics of the magnet have been studied for different values of operating current. We report on a new and rather unexpected behaviour of the HTS magnets at different operating conditions, together with a theoretical explanation.