Abstract

To create the windings of the magnetic system of the Future Circular Collider, it is necessary to modernize the Nb₃Sn-based composite superconductors obtained by the method of internal tin sources, which also involves an increase in the thermal conductivity and electrical conductivity of the matrix copper as determined using the residual resistance ratio (RRR) parameter (the ratio of the values of the electrical resistivity of copper at 273 and 20 K). The achievement of high RRR values is controlled by the balance between the geometric dimensions, the volume fractions of the superconductor components, and the mode of reaction heat treatment (RHT) used for the formation of the Nb₃Sn phase. The results of an experimental and theoretical study of the effect of the strand diameter and the RHT mode on the RRR parameter are given. The diffusion of tin from the zone of subelements into the stabilizing copper in the course of RHT in strands of various diameters has been investigated by scanning electron microscopy and electron probe microanalysis. The study was carried out on experimental samples of multifilamentary superconductors based on Nb₃Sn with a distributed Nb barrier.

中文翻译：

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含内部锡源的Nb 3 Sn基超导体扩散退火对稳定铜电导率的影响

摘要

要创建未来圆形对撞机的磁系统绕组，有必要对通过内部锡源方法获得的Nb ₃ Sn基复合超导体进行现代化改造，这还涉及到提高其热导率和电导率。使用剩余电阻率（RRR）参数（铜在273和20 K时的电阻率值之比）确定的基体铜。通过几何尺寸，超导体组分的体积分数以及用于形成Nb ₃的反应热处理（RHT）模式之间的平衡来控制获得高RRR值锡相。给出了绞合线直径和RHT模式对RRR参数影响的实验和理论研究的结果。通过扫描电子显微镜和电子探针显微分析，研究了锡在RHT过程中以不同直径分布在子元素区域中扩散到稳定的铜中。该研究是基于具有分布Nb势垒的Nb ₃ Sn的多丝超导体的实验样品进行的。