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Screening current in ultra-high-field non-insulated superconducting magnets

Science China(Technological Sciences) 2024年第7期67卷 2255-2273页

作者： ZHOU BenZhe wang Lei CHEN Yong wang qiuliang wang KangShuai ZHANG ZiLi LIU JianHua University of Chinese Academy of Sciences Beijing 100049China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China

Screening current is recognized as one of the critical elements limiting the progression of superconducting magnets toward achieving higher magnetic fields. Currently, most non-insulated(NI) superconducting magnets consider the magnet as insulated when addressing the issue of screening current. However, the bypass current in the NI magnet can modify the actual history of magnetization, so the screening current in NI magnet will be different from that in the insulated magnet. This paper presents a novel method based on the homogenized T-A formulation(T is the current vector potential, and A is the magnetic vector potential), which enables real-time simulation of both the bypass current behavior and the implications of screening current in NI superconducting magnets, even when these magnets contain tens of thousands of turns. We have developed a 32 T NI hybrid superconducting magnet and validated the effectiveness of this method through experiments. Employing this efficacious method,we conducted a comprehensive calculation of screening current in NI magnets, comparing them with insulated magnets in terms of screening current-induced stress(SCIS), screening current-induced field(SCIF), and losses. The results indicate that in the NI insert coils, the sequential excitation of background coils and insert coils induces a reverse screening current, resulting in slightly lower SCIF and SCIS compared to those in the insulated magnets. The method and results can contribute to the enhancement of magnet design and provide valuable insights for the development of ultra-high fields(UHF) NI magnets.

关键词： ultra-high-field superconducting magnet screening current REBCO coil NI coil stress loss

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Gradient coil design with enhanced shielding constraint for a cryogen-free superconducting MRI system

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Magnetic Resonance Letters 2024年第1期4卷 1-9页

作者： Yaohui wang Weimin wang Hui Liu Shunzhong Chen Feng Liu qiuliang wang Institute of Electrical Engineering Chinese Academy of SciencesBeijing100190China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing100049China School of Electronics&Institute of Biomedical Engineering Peking University&Shenzhen Graduate SchoolShenzhen518055China School of Information Technology and Electrical Engineering The University of QueenslandSt LuciaBrisbaneQLD4072Australia

The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI *** this study,we present an enhanced shielding method incorporating a regionalized stray field constraining *** optimizing the constraint parameters,we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by *** real measurement in an integrated MRI system,the developed gradient assembly demonstrated good performance and supported to output images of excellent *** findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.

关键词： MRI Gradient coil Superconducting magnet Cryogen-free Magnetic shielding

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Achievement of a high-performance 30-tesla metal-as-insulated user superconducting magnet

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Science China(Technological Sciences) 2024年第6期67卷 1974-1978页

作者： ZHOU BenZhe DAI YinMing ZHANG ZiLi LIU Hui wang YaoHui wang Lei wang Hui CHEN ShunZhong wang KangShuai CHEN Yong LIU JianHua wang qiuliang Institute of Electrical Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences

Strong magnetic fields can be used to manipulate the states of matter and induce unique ***,they enable a thorough investigation of the intrinsic properties of matter through the application of the nuclear magnetic resonance(NMR)*** versatile nature of strong magnetic fields facilitates the discovery of novel phenomena and patterns.

关键词： effect NMR versatile

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Effect of Magnetic Field Configuration on Stray-Crystal Formation with Different Platform Sizes during Directional Solidification of Single-Crystal Superalloy

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 904-914页

作者： Keke Lu Congjiang Zhang Xiaotan Yuan Hongbin Yu Weili Ren Biao Ding Haibiao Lu Yunbo Zhong Zuosheng Lei Hui wang qiuliang wang Peter KLiaw Xuezhi Qin Lanzhang Zhou State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced FerrometallurgyShanghai UniversityShanghai 200444China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The magnetic field is an effective means to control the solidification structure and the defects of metal and semiconductor *** work investigates the effects of Cusp magnetic field(CMF)and longitudinal magnetic field(LMF)on the stray-crystal formation in the platform regions during the directional solidification of single-crystal superalloy with the different cross section *** application of CMF reduces the formation of platform stray-crystal,while LMF increases its *** the platform size increases,the stray-crystal ratio increases regardless of whether the magnetic fields are applied or not,the effectiveness of CMF increases,while that of LMF *** reason that the effects of CMF and LMF on the platform stray-crystal formation could be attributed to the change of flow structure from the distribution characteristics of the thermoelectric magnetic force and the magnetic damping force near the liquid-solid interface.

关键词： Stray-crystal Magnetic field Single-crystal superalloy Cross section change Directional solidification

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多学科融合共促碳达峰与碳中和

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科学通报 2024年第8期69卷 981-982页

作者：张涛王秋良中国科学院大连化学物理研究所大连116023 中国科学院电工研究所北京100190

实现碳达峰碳中和(简称“双碳”),是以习近平同志为核心的党中央统筹国内国际两个大局作出的重大战略决策.党的二十大报告明确提出,要积极稳妥推进碳达峰碳中和,深入推进能源革命,加快规划建设新型能源体系,推动能源清洁低碳高效利用,... 详细信息

实现碳达峰碳中和(简称“双碳”),是以习近平同志为核心的党中央统筹国内国际两个大局作出的重大战略决策.党的二十大报告明确提出,要积极稳妥推进碳达峰碳中和,深入推进能源革命,加快规划建设新型能源体系,推动能源清洁低碳高效利用,确保能源安全,提升生态系统碳汇能力,加快发展方式绿色转型.

关键词：碳中和能源革命绿色转型多学科融合能源安全战略决策生态系统低碳高效

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Nb_(3)Sn超导线材中Ta层的去除及腐蚀机理

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金属学报 2024年第7期60卷 968-976页

作者：高瞻张泽荣程军胜王秋良中国科学技术大学稀土学院合肥230026 中国科学院赣江创新研究院赣州341119 中国科学院电工研究所北京100190

高质量的超导接头对于超导磁体的建造和后期稳定运行有着关键的作用。然而,针对Nb_(3)Sn线材,常常因为内部Ta阻挡层的存在而影响超导接头的制备。为了探究Nb_(3)Sn超导线材中Ta阻挡层的去除方法,选取内锡法制备的Nb_(3)Sn超导线材为实... 详细信息

高质量的超导接头对于超导磁体的建造和后期稳定运行有着关键的作用。然而,针对Nb_(3)Sn线材,常常因为内部Ta阻挡层的存在而影响超导接头的制备。为了探究Nb_(3)Sn超导线材中Ta阻挡层的去除方法,选取内锡法制备的Nb_(3)Sn超导线材为实验对象,研究了线材在HF溶液、HF气氛、HF和H_(2)O_(2)混合溶液以及HF和HNO_(3)混合溶液中的腐蚀行为和特征,利用SEM和OM分析了线材微观结构和腐蚀形貌。结果表明,Ta层在HF和HNO_(3)混合溶液中腐蚀最快,在HF和H_(2)O_(2)混合溶液中次之,在HF气氛中较慢,在HF溶液中最慢。综合腐蚀后效果,采用HF和H_(2)O_(2)混合溶液进行腐蚀是去除Nb_(3)Sn超导线材中Ta阻挡层的最佳方法。同时,选取高纯Ta片为研究对象,分别在上述介质中进行腐蚀实验,并通过OM、XRD和XPS观察和分析试样腐蚀形貌、物相结构变化和腐蚀溶液中的元素价态,揭示了Ta的腐蚀机理,氧化剂的存在可以通过加快Ta表面Ta_(2)O_(5)膜的形成来加快HF对Ta的腐蚀速率。

关键词： Nb_(3)Sn超导线超导接头 Ta HF腐蚀

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高温超导内插磁体偏移的力磁耦合分析

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低温与超导 2024年第6期52卷 13-19页

作者：徐申楠王秋良刘建华齐磊华北电力大学电气与电子工程学院北京102206 中国科学院电工研究所北京100190

为探究内插线圈偏移问题对磁场均匀度的影响,利用有限元软件针对15 T高温超导内插磁体建立了完整的三维力磁耦合仿真数值模型,计算线圈偏移时的电磁力,分析稳态下的位移变化,采用敏度分析研究偏移量与磁场均匀度的关系。结果显示,磁场... 详细信息

为探究内插线圈偏移问题对磁场均匀度的影响,利用有限元软件针对15 T高温超导内插磁体建立了完整的三维力磁耦合仿真数值模型,计算线圈偏移时的电磁力,分析稳态下的位移变化,采用敏度分析研究偏移量与磁场均匀度的关系。结果显示,磁场均匀度对内线圈偏移更敏感,偏移量保持在0.5 mm时能够将磁场均匀度保持较高水平。

关键词：高温超导内插磁体偏移力磁耦合磁场均匀度

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High-Speed Visualization of Bubble Behaviors for Pool Boiling of R-141b

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Journal of Thermal Science 2006年第1期15卷 79-84,96页

作者： Yanhua DIAO Yaohua ZHAO qiuliang wang Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100080 China The College of Architecture and Civil Engineering Beijing University of Technology Beijing 100022 China

A visualization study on the behavior of bubbles has been carried out for pool boiling of R141b on a horizontal transparent heater at pressure 0.1 MPa. The behaviors of bubbles were recorded by a high-speed camera placed beneath the heater surface. The departure diameter, departure time of bubbles and nucleation site density at different heat flux were obtained. The visualization results show that bubble departure diameter and departure time decrease, while the nucleation site density increases as the heat flux increases. R is also observed that there is no liquid recruited into the microlayer in the experiment. Based on the experimental results, boiling curve for R141b was predicted by using the dynamic microlayer model. As a resuR, the agreement between the predictive result based on the dynamic microlayer model and the experiment data for boiling curve of R141b is good at high heat flux.

关键词： R141b heat transfer bubble dynamics pool boiling.

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基于黑云母粉的复合水凝胶的制备及太阳能水蒸发性能研究

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合肥工业大学学报（自然科学版） 2024年第7期47卷 948-951页

作者：王秋亮薛敬哲陈胜陆杨合肥工业大学化学与化工学院安徽合肥230009

文章以黑云母粉为光热转换材料、聚乙烯醇和壳聚糖为凝胶基底材料,经交联和冻融处理制备基于云母的复合水凝胶。通过X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)以及扫描电子显微镜-能量散射X射线光谱(scanning electron mi... 详细信息

文章以黑云母粉为光热转换材料、聚乙烯醇和壳聚糖为凝胶基底材料,经交联和冻融处理制备基于云母的复合水凝胶。通过X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)以及扫描电子显微镜-能量散射X射线光谱(scanning electron microscopy-energy dispersive X-ray spectroscopy,SEM-EDS)分析技术确定黑云母粉含有铁元素,其质量分数约为3.86%。片层状结构黑云母粉的加入使水凝胶的压缩应力提升1倍以上,显著增强了水凝胶的力学性能。复合水凝胶的太阳能水蒸发速率可以达到1.52 kg/(m^(2)·h)。

关键词：黑云母粉太阳能光热转换材料水凝胶复合材料太阳能水蒸发

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Microstructure evolution of Nb_3Sn superconductors during diffusion treatment by bronze route

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Rare Metals 2012年第5期31卷 446-450页

作者： CHENG Junsheng wang qiuliang wang Hui DAI Yinming Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China

The element diffusion process of Nb_3Sn superconductors by bronze route was studied using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The critical current of superconductors was measured by four-point method. The results show that a diffusion layer has formed around the boundaries between the filaments and bronze matrix after 15 h heat treatment. The diffusion layer thickness keeps stable after heat treatment duration of 50~75 h. The stable and solid Nb 3 Sn layer is obtained in the sample after 100 h heat treatment. Excessive heat treatment would induce superconductivity degeneration because of superconductor grain coarsening. The characteristics of the element diffusion process were discussed. The diffusion of tin atom is the governing factor in diffusion. In this study, Nb_3_Sn superconductors with good superconducting property were fabricated successfully at 670 °C after 100h heat treatment.

关键词： Nb_3Sn diffusion treatment bronze route critical current

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