在MgB_2 /Fe超导带材中,Fe包套与MgB_2超导芯的交界处有很薄的反应层,其主要成分为Fe_2B和FeB,其电阻率很高,导致当电流在基材和超导芯间转移时存在一个转移长度,在这一长度上会产生电压分布并伴随有焦耳热产生,从而影响到带材的临界电流测量和热稳定性.本文使用分布电阻模型分析了MgB_2 /Fe超导带材中的电流转移特点,推导出电流转移长度的公式及由于电流转移产生的焦耳热,并把电流转移产生的焦耳热加入到MgB_2/Fe超导带材在绝热条件下失超传播的一维分析当中,推导出失超传播速度的公式,对超导带材失超传播速度的传统计算公式进行了改进,本文对研究MgB_2 /Fe复合超导带材的热稳定性分析及MgB_2超导带材的实用化具有参考价值.
In MgB_2/Fe tape, a reaction layer (Fe_2B and FeB) is formed between Fe sheath and MgB_2 core during heat treatment. This layer has relatively high electrical resistivity and also low thermal conductivity. The current transfer exists between Fe sheath and MgB_2 core because of the reaction layer. An equivalent circuit model was establisbed in order to study the current transfer processes in MgB_2/Fe tape. The current transfer processes brings more Joule heating when a segment of MgB_2 filament transform from superconducting to normal state. So the current transfer can affect the stability of MgB_2/Fe tape. The traditional calculation formula for the quench propagation velocities was improved. The numerical model is useful in studying the stability of MgB_2/Fe tape.
参考文献
| [1] | Andrea Kasztler;Michael Foitl;Hans Kirchmayr;Milan Polak;Milan Majoros .Critical current variation and current transfer length in multifilamentary Bi-2223/Ag tapes[J].IEEE Transactions on Applied Superconductivity: A Publication of the IEEE Superconductivity Committee,1999(2 Pt.2):2340-2342. |
| [2] | T Holubek;M Dhalle;P Kovac .Current transfer in MgB_2 wires with different sheath materials[J].Superconductor Science & Technology,2007(3):123-128. |
| [3] | T Holubek;P Kovac;T Melisek .Current transfer length in MgB_2/Fe mono-core wire and approximation of the interface layer resistivity[J].Superconductor Science & Technology,2005(9):1218-1221. |
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