Ternary Nb3Sn superconductors with artificial pinning centers and high upper critical fields
Ternary Nb3Sn superconductors with artificial pinning centers and high upper critical fields
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具有人工钉扎中心和高上临界场的三元 Nb3Sn 超导体
DOI：
10.1088/1361-6668/aaf7ca
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发表时间：
2018
影响因子：
3.6
通讯作者：
M. Tomsic
中科院分区：
文献类型：
--
作者：
X. Xu;J. Rochester;X. Peng;M. Sumption;M. Tomsic
在这封信中，我们展示了三元Nb 3Sn多芯导体与人工钉扎中心（APC），实现高临界场的发展。在31 T磁体上进行了测试，结果表明，它们在4.2 K时的上临界磁场（Bc 2）值为27-28 T，不可逆磁场（Birr）值大于26 T，接近或高于最佳棒再堆工艺（RRP）导体。在16 T和4.2 K下，非Cu Jc已经达到接近1200 A mm−2，与RRP相当，尽管由于导体设计和热处理尚未优化，细丝中的细晶粒Nb 3Sn分数仍然很低（20%-30%），晶粒尺寸仍然没有完全细化（70-80 nm）。对于具有1%Zr的APC导线，Nb 3Sn层Jc在4.2 K、16 T下为4710 A mm-2，比RRP导体高约2.5倍，尽管其晶粒尺寸由于氧不足和未优化的热处理而尚未完全细化。分析了通过进一步优化APC导体及其热处理工艺可以获得的非Cu Jc。
In this letter we demonstrate the development of ternary Nb3Sn multifilamentary conductors with artificial pinning centers (APC) which achieve high critical fields. These recently-developed conductors were tested in a 31 T magnet, and the results showed that their upper critical field (Bc2) values at 4.2 K are 27–28 T, and irreversible field (Birr) values are above 26 T, values similar to or higher than those of best rod-restack-process (RRP) conductors. The non-Cu Jc has been brought to nearly 1200 A mm−2 at 16 T and 4.2 K, comparable to RRP, in spite of the fact that the fine-grain Nb3Sn fractions in filaments are still low (20%–30%) and the grain sizes are still not fully refined (70–80 nm) due to conductor designs and heat treatments that are not yet optimized. The Nb3Sn layer Jc at 4.2 K, 16 T is 4710 A mm−2 for the APC wire with 1%Zr, about 2.5 times higher than RRP conductors, in spite of the fact that its grain size is not yet fully refined due to insufficient oxygen and unoptimized heat treatment. An analysis is presented about the non-Cu Jc that can be achieved by further optimizing the APC conductors and their heat treatments.