Development of superconducting model dipole magnets beyond 12 T with a combined common-coil configuration
Development of superconducting model dipole magnets beyond 12 T with a combined common-coil configuration
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DOI：
10.1088/1361-6668/acc615
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发表时间：
2023-03
影响因子：
3.6
通讯作者：
Chengtao Wang;Yingzhe Wang;Jinrui Shi;Z. Feng;Chunyan Li;Juan Wang;R. Kang;Wei Li;A. Feng
中科院分区：
文献类型：
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作者：
Chengtao Wang;Yingzhe Wang;Jinrui Shi;Z. Feng;Chunyan Li;Juan Wang;R. Kang;Wei Li;A. Feng
IHEP的超导磁体组（中国科学院高能物理研究所）自2014年以来一直从事高场加速器磁体的研发，用于CEPC-SPPC等下一代高能粒子加速器的预研（圆形正负电子对撞机-超级质子对撞机）2017年首次用NbTi和Nb 3Sn以组合共线圈配置制造了名为LPF 1的超导模型偶极磁体，并于2018年进行了测试。在两个10 mm孔径内达到10.23 T的主磁场。磁体于2019年以较高预应力重新组装，以研究预应力加载水平对共线圈偶极磁体性能的影响。这款名为LPF 1-S的升级磁体的主磁场在两个12 mm孔径内增加到10.71 T。通过改进卢瑟福电缆制造、线圈绕制、Nb 3Sn和NbTi接头焊接和线圈浸渍等关键工艺，最近制造的模型偶极磁体LPF 1-U于2021年在两个14 mm孔径中获得12. 47 T的主磁场。为了充分利用Nb 3Sn和NbTi超导体在不同场区的优势，LPF 1-U仍然设计和开发了组合线圈配置，其中Nb 3Sn用于内部两个线圈，NbTi用于外部四个线圈。此外，在LPF 1-U布局的优化中，采用了分级线圈拓扑和不同的线圈LSS（直线段长度）设置。支撑结构采用气囊和关键技术，并利用基于光纤布拉格光栅（Fiber Bragg Grating）的光纤传感器监测从磁体组装到冷却和激励的整个过程中结构和线圈的应力分布和变化。在性能测试期间，进行了相对大量的训练，并且LPF 1-U在热循环之后变得更加稳定。线圈中的峰值场为12.7T（孔中的主场为12.47T），对应于6865 A的工作电流，最终获得90%的负载线比率。值得一提的是，LPF 1-U是第一个混合Nb 3Sn，NbTi-共线圈偶极磁体，在两个孔径中实现了超过12 T的主磁场。本文介绍了LPF系列双极磁体的设计、制作和性能分析。
The superconducting magnet group at IHEP (the Institute of High Energy Physics, Chinese Academy of Sciences, China) has been engaging in the R&D of high field accelerator magnets since 2014 for the pre-study of the next-generation high energy particle accelerators like CEPC-SPPC (Circular Electron Positron Collider-Super Proton Proton Collider), FCC (Future Circular Collider), etc. A superconducting model dipole magnet named LPF1 was first fabricated with NbTi and Nb3Sn in a combined common-coil configuration in 2017 and tested in 2018, a main field of 10.23 T was reached within two 10 mm apertures. The magnet was reassembled with higher pre-stress in 2019 to investigate the influence of the pre-stress loading level on the performance of common-coil dipole magnets. The main field of this upgraded magnet named LPF1-S was increased to 10.71 T within two 12 mm apertures. By improving the key processing technologies in Rutherford cable fabrication, coil winding, Nb3Sn & NbTi splices soldering and coil impregnation, the recently fabricated model dipole magnet named LPF1-U attained a 12.47 T main field in two 14 mm apertures in 2021. To fully take advantage of Nb3Sn and NbTi superconductors in different field regions, LPF1-U was still designed and developed with a combined coil configuration with Nb3Sn for the inner two coils and NbTi for the outer four coils. Additionally, graded coil topology and different coil LSS (length of straight section) settings were adopted in the optimization of LPF1-U layouts. Bladder and key technology was used for the support structure, and fiber optic sensors based on FBG (fiber Bragg grating) were utilized to monitor the stress distribution and variation in the structures and coils through the whole process from magnet assembly to cool-down and excitation. During the performance test, a relatively large number of trainings were carried out and LPF1-U became more stable after the thermal cycle. A peak field of 12.7 T in the coils (12.47 T main field in apertures) corresponds to an operating current of 6865 A and a load line ratio of 90% was finally attained. It is worth mentioning that LPF1-U is the first hybrid—Nb3Sn, NbTi—common coil dipole magnet that has achieved a main field of more than 12 T in two apertures. The design, fabrication and performance analysis of the LPF series dipole magnets are presented in this paper.