Effect of Copper Resistivity and Filament Size on the Self-Field Instability of High-Jc Nb3Sn Strands
Effect of Copper Resistivity and Filament Size on the Self-Field Instability of High-Jc Nb3Sn Strands
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DOI：
10.1109/tasc.2012.2235119
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发表时间：
2013-06-01
影响因子：
1.8
通讯作者：
Ghosh, Arup K.
中科院分区：
文献类型：
--
作者：
Ghosh, Arup K.
具有大细丝和高J（c）的Nb 3Sn股线在变化的磁场中在低磁场下由于磁化通量跳跃而表现出不稳定性。此外，在5至7 T的中间磁场下，这些股线在远低于临界电流的电流下过早淬灭。电流-电压测量通常用于确定临界电流，并且观察到的过早淬火是由股线内的电流重新分布驱动的，因为电流增加，并且被称为“自场”不稳定性。当温度从4.2 K降低到2 K时，这种不稳定性加剧。先前的一项研究在“准绝热”极限下检查了导线，其中动态热传递机制被抑制。在本文中，我们报告的测量温度范围为4.2-2 K的高J（c）RRP股不同的铜稳定剂结晶度和Nb 3Sn丝直径。这些测量表明，铜稳定剂的残余电阻率比RRR在减轻这种不稳定性方面起着重要作用。同样对于具有类似RRR的股线，我们发现稳定性随着长丝直径的减小而改善，尽管改善不是非常显著。
Nb3Sn strands with large filaments and high-J(c) exhibit instabilities due to magnetization flux-jumps at low fields in changing magnetic fields. In addition, at intermediate fields of 5 to 7 T, these strands quench prematurely at currents well below the critical current. Current-voltage measurements are typically used for critical current determinations, and the premature quenching observed is driven by current redistribution within the strand as the current is increased and is termed "self-field" instability. This instability is exacerbated as the temperature is lowered from 4.2 K to 2 K superfluid helium. A previous study examined wires in the "quasi-adiabatic" limit, where dynamic heat transfer mechanisms are suppressed. In this paper, we report on measurements in the temperature range of 4.2-2 K on high-J(c) RRP strands with varying copper stabilizer resistivities and Nb3Sn filament diameters. These measurements show that the residual resistivity ratio, RRR, of the copper stabilizer plays an important role in mitigating this instability. Also for strands with similar RRR, we find that the stability improves with decreasing filament diameters, although the improvement is not very dramatic.