Review of Nb3Sn conductors for ITER
Review of Nb3Sn conductors for ITER
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DOI：
10.1016/j.fusengdes.2007.01.024
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
D. Ciazynski
中科院分区：
文献类型：
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作者：
D. Ciazynski
ITER高磁场磁体（> 11 T）、中心螺线管（CS）和环向场（TF）系统将使用Nb 3Sn作为超导材料的复合导体。这种超导体在温度和磁场方面提供了所需的能力，但对应变敏感。2000-2002年的两个ITER模型线圈，CS模型线圈（CSMC）和TF模型线圈（TFMC）的测试在ITER磁体的工业可行性和操作能力的信心。然而，仔细的分析表明，温度裕度下降。利用超导体工业自模型线圈制造以来所取得的进展，ITER Nb 3Sn导体已经使用更高性能（高级）股线重新设计，以恢复原始设计的温度裕度，而不改变导体包络。在ITER参与者团队（PT）中启动了一项研发计划，以了解退化的来源，发现可能是电磁负载下电缆内部的股线弯曲。与此同时，新的绞线被订购给工业公司，以制造和测试全尺寸的导体。欧盟PT在2006年年中测试了两个全尺寸导体样品，这些样品采用先进的Nb 3Sn绞线，但使用TFMC导体设计，它们在绞线性能和ITER TF导体设计方面的性能远低于预期。整体性能并不比TFMC导体样品性能高多少。这种较差的性能归因于对高级股线的变形更敏感。然而，需要对真实的ITER TF导体样品进行测试才能得出最终结论。第一批样本应于2006年底和2007年进行测试。然而，人们必须已经准备好重新设计热核实验堆导体，以及修改和调整股规格，使用自模型线圈测试以来开发的新工具（测试设施，机械模型）。此外，将股线和全尺寸短样品测试结果外推到ITER线圈的方法并不简单，必须在ITER团队和ITER PT之间达成一致。
The ITER magnets experiencing high magnetic field (>11T), the central solenoid (CS) and the toroidal field (TF) system, will make use of complex conductors using Nb3Sn as superconducting material. This superconductor offers the required capability in temperature and magnetic field but shows sensitivity to strain. The two ITER model coils, the CS model coil (CSMC) and the TF model coil (TFMC) tested in 2000–2002 have given confidence in the industrial feasibility and the operating capability of the ITER magnets. However, careful analyses have revealed a degradation in terms of temperature margin. Taking advantage of the progress made by the superconductor industry since the model coil fabrications, the ITER Nb3Sn conductors have been redesigned using higher performance (advanced) strands to recover the original designed temperature margin without changing the conductor envelopes. An R&D program was launched among the ITER participant teams (PTs) to understand the source of degradation which was found to be likely the bending of the strands inside the cable under the electromagnetic load. Meanwhile, new strands were ordered to industrial companies, to manufacture and to test full-size conductors. The European Union PT tested by mid-2006 two full-size conductor samples with advanced Nb3Sn strands but using the TFMC conductor design, they showed performance much below expectation with regard to strand performance and to ITER TF conductor design. Overall performance is not much above the TFMC conductor sample performance. This poor performance has been attributed to more sensitivity to deformation of advanced strands. Nevertheless, tests of real ITER TF conductor samples are needed to draw final conclusions. The first samples should be tested at the end of 2006 and in 2007. However, one must already be prepared to redesign the ITER conductors as well as to modify and adapt the strand specifications, using the new tools (test facilities, mechanical models) developed since the model coil tests. In addition, the way to extrapolate strand and full-size short sample test results to ITER coils is not straightforward and has to be agreed among the ITER team and the ITER PTs.