托卡马克聚变堆中环向磁场超导线圈的磁弹性弯曲与稳定性

本文针对托卡马克装置中超导载流磁体的磁弹性弯曲与稳定性问题，运用Ｂｉｏｔ－Ｓａｖａｒｔ定律和曲梁弯曲理论，给出了其环向磁场的超导载流线圈结构在自身电流产生的磁力作用下的磁弹性力学模型。所得到的控制方程反映了磁场与线圈变形之间的非线性耦合作用，全面描述了结构的轴向拉伸、绕轴扭转、面内弯曲和面外弯曲等各种变形模式。本文采用半解析半数值方法对控制方程进行了定量求解，获得了有关线圈形变和内力分布的定量结果。通过其面外弯曲变形与外加电流的非线性关系，应用Ｓｏｕｔｈｗｅｌ图，给出了线圈在磁弹性相互作用下发生磁弹性失稳的临界电流值，并讨论了临界电流随环向磁场线圈个数变化的规律     

25T超导磁体优化中线圈数量影响分析

20 T以上强磁场在高场科学工程中有着不可替代的作用. 电工研究所正在研制一个25 T全超导磁体系统, 包括15 T背景磁场和10 T高温超导内插磁体. 在磁体的设计和优化中, 线圈的数量和种类对于最终优化结果十分关键. 为了研究磁体数量和磁体相关参数的关系, 计算了20 组不同的线圈组合下磁体的优化结果. 优化中除了考虑必要的限制条件以外, 还采用了一种结合局部优化算法和全局优化算法的方法. 通过对比分析发现, 线圈数量和磁体造价之间, 存在一个“V”形的关系. 更进一步地, 本文分析了不同超导体在磁体中应该贡献的最佳磁场, 以及背景磁体统一供电给优化结果带来的影响.     

CFETR纵场磁体线圈内馈线结构设计与分析

介绍了中国核聚变工程试验堆(CFETR)纵场磁体线圈馈线系统内馈线的结构,它由外盒体、万向节、 超导母线与冷却管路以及内部支撑架等子部件组成。在纵场磁体线圈内馈线工况下,对其进行了结构设计,并通 过有限元分析,获得了内馈线工作状态下的应力和位移分布云图。结果表明,最大应力与最大位移变形均满足设 计使用要求。      

RIKEN超导ECR离子源磁体系统的设计

Superconducting magnet system for a 28GHz ECR ion source has been designed.The maximum axial magnetic fields are 4T at the rf injection side and 2T at the beam extraction side,respectively.The hexapole magnetic field is about 2T on the inner surface of the plasma chamber.The superconducting coils consist of six solenoids and six racetrack windings for a hexapole field.Two kinds of coil arrangements were investigated:one is an arrangement in which the hexpole coil is located in the bore of the solenoids,and another is the reverse of it.The coils use NbTi-Copper conductor and are bath-cooled in liquid helium.The six solenoids are excited with individual power supplies to search for the optimal axial field distribution.The current leads use high Tc material and the cryogenic system is operated in LHe re-condensation mode using small refrigerators.The thermal insulated supports of the cold mass have also been designed based on the calculated results of the magnetic force.The heat loads to 70K and LHe stages were estimated from the design of the supports,the current leads and so on.     

超导离子源铌三锡六极线圈镜像磁场约束结构的优化设计

中国科学院近代物理研究所正在进行国际首台45 GHz全铌三锡超导离子源FECR(Fourth Electron Cyclotron Resonance)磁体的研制,该离子源磁体线圈由六个铌三锡超导六极线圈和四个铌三锡超导螺线管线圈组成。由于单根超导线绕制异形六极线圈(非标准鞍型)技术难度大,且铌三锡超导性能对应力敏感,为了测试单个铌三锡六极线圈性能能否达到设计指标,基于铝合金壳层结构和Bladder-Key精确预紧技术,设计了镜像磁场约束结构。本工作主要阐述了运用ANSYS参数化设计编程对镜像磁场结构进行优化设计的过程和优化后的镜像磁场结构,确定了室温预应力大小,并给出了线圈经过室温预紧、冷却降温和加电励磁后的最大等效应力。进一步结合实际六极线圈制作公差(±0.1 mm),分析和评估了公差对镜像磁场结构中六极线圈预应力施加的影响。     

超导线圈绕制过程的力学行为研究

为了增加超导线圈中导线的占空比, 提高超导磁体正常运行时的机械稳定性, 通常在超导线圈绕制过程中施加一定的绕制张紧力. 绕制张紧力的大小会对超导磁体的失超特性和退化性能产生重要的影响, 因此有必要对绕制过程中的机械应力进行详细的分析. 本文仔细地分析了绕制过程中导线的受力情况, 进行了一些合理的假设和近似, 提出了研究超导线圈绕制应力的理论模型, 并根据轴对称结构的弹性力学方程式推导了计算超导线圈应力应变分布的理论公式. 基于该模型分别研究了单一绕组的超导线圈和双绕组的超导线圈的绕制应力, 分析了绕制张紧力和绕组的各向异性特性对径向应力和环向应力的影响. 在该理论模型分析结果的基础上可以进一步分析多物理场作用下的超导磁体的应力应变行为, 为高性能超导线圈的设计和建造提供理论指导. 关键词： 超导线圈 机械稳定性 绕制张力 应力     

Globally optimal superconducting magnets part II: symmetric MSE coil arrangement

A globally optimal superconducting magnet coil design procedure based on the Minimum Stored Energy (MSE) current density map is outlined. The method has the ability to arrange coils in a manner that generates a strong and homogeneous axial magnetic field over a predefined region, and ensures the stray field external to the assembly and peak magnetic field at the wires are in acceptable ranges. The outlined strategy of allocating coils within a given domain suggests that coils should be placed around the perimeter of the domain with adjacent coils possessing alternating winding directions for optimum performance. The underlying current density maps from which the coils themselves are derived are unique, and optimized to possess minimal stored energy. Therefore, the method produces magnet designs with the lowest possible overall stored energy. Optimal coil layouts are provided for unshielded and shielded short bore symmetric superconducting magnets.     

ITER 超导馈线系统的设计

ITER( 国际热核试验堆) 采用超导馈线系统传输磁体线圈所需电流、冷却液及数据信号, 并在失超等异常情况, 通过馈线转移磁体能量, 以保护整个磁体系统。介绍了国际热核试验堆超导馈线系统的结构及设计情况, 为同类型超导磁体的馈线设计提供了有益的参考。     

FAIR项目super-FRS超导磁体结构分析

 国际反质子与离子大科学工程项目中的超导super-FRS磁体包含2个超导线圈,最大磁场为1.6 T,这样大的磁场必然产生很大的电磁力。为了保证磁体运行时的机械稳定性,对项目中的超导super-FRS磁体进行了有限元结构的3维分析。结构分析中采用了ADINA和TOSCA两个有限元软件。ADINA软件主要用于结构中的应力应变计算,而TOSCA软件则主要用于电磁场的磁场强度和电磁力的计算。分析的结果显示super-FRS磁体采用铁芯及线圈盒长边中部加固结构时,其最大形变约0.19 mm,最大有效应力出现在长边中部的很小区域,约为92 MPa。由于线圈盒由316LN不锈钢制成,该结构是合理的。     

5T有源屏蔽式超导磁体结构设计

介绍了为兰州Penning离子阱项目专门设计的5T有源屏蔽式超导磁体。 为达到物理设计要求的场均匀度, 超导磁体有3层共计6个线包组成。 同时为了确保线圈绕制的定位精度和在强磁场下的稳定性, 绕制骨架采用三筒体结构, 模拟计算表明线圈的绝缘和固定结构能够达到强磁场下的电气和机械性能要求。 对5T有源屏蔽式超导磁体结构设计材料选择以及线圈的绕制工艺进行了详细的论述。 A 5T actively shielded superconducting magnet was designed for Lanzhou Penning Trap project. In order to achieve homogeneity of physical requirements, superconducting magnet was made up of six coils, which were wound on framework of three layers. Meanwhile, three framework structure can ensure the precision of coil winding and the mechanical stability under intense magnetic field. The results of simulation show that the insulation and fixed structure of the coil can satisfy the electrical and mechanical requirements under intense magnetic field. At last, properties of the used materials and coil fabrication have been presented.     

短腔、自屏蔽磁共振成像超导磁体系统的混合优化设计方法

本文提出一种用于短腔、自屏蔽磁共振成像超导磁体系统的混合优化设计方法,通过结合线性规划和非线性优化算法,设计出的磁体系统具有建造成本低、结构简单、以及线圈中最高磁场、电流安全裕度和电磁应力可控等优点.首先,通过线性规划算法在欲布置线圈空间范围内建立二维连续网格划分,搜索满足磁场约束条件的网格电流分布图;其次,将电流分布图中的非零电流簇离散成螺线管线圈,通过非线性优化算法计算出满足成像区域磁场均匀度要求、5 Gs杂散场限制、线圈中最高磁场限制、电流安全裕度以及线圈间尺寸间隔等约束条件的线圈结构参数.文中给出一个中心磁场为1.5T自屏蔽磁共振成像超导磁体系统的设计案例,在50 cm球形成像区域所产生的磁场峰峰值不均匀度为10 ppm,线圈最大长度为1.32 m.该设计方法可用于对称、非对称螺线管线圈系统以及开放式双平面线圈系统的磁共振成像磁体系统设计.     

Design of a superconducting magnet for CADS

This paper describes a superconducting magnet system for the China Accelerator Driven System (CADS). The magnetic field is provided by one main, two bucking and four racetrack coils. The main coil produces a central field of up to 7 T and the effective length is more than 140 mm, the two bucking coils can shield most of the fringe field, and the four racetrack superconducting coils produce the steering magnetic field. Its leakage field in the cavity zone is about 5× 10^-5 T when the shielding material Niobium and cryogenic permalloy are used as the Meissner shielding and passive shielding respectively. The quench calculations and protection system are also discussed.     

Levitating states of superconducting rings in the field of a fixed ring with constant current

We consider the possibility of designing a plasma trap with a magnetic system formed by super-conducting rings and coils levitating in the field of a fixed coaxial coil carrying constant current. An analytic dependence of the potential energy of such a system with one or two levitating superconducting rings having trapped preset magnetic fluxes on their coordinates in the uniform gravitational field is obtained in the thin ring approximation. Calculations performed in the Mathcad system show that equilibrium states of such a system exist for certain values of parameters. Levitating states of a single superconducting ring and two superconducting rings in the field of the coil with constant current are observed experimentally in positions corresponding to calculated values.     

Modeling the static fringe field of superconducting magnets

The resonance frequency-space and the frequency gradient-space relations are evaluated analytically for the static fringe magnetic field of superconducting magnets used in the NMR diffusion measurements. The model takes into account the actual design of the high-homogeneity magnet coil system that consists of the main coil and the cryoshim coils and enables a precise calibration of the on-axis magnetic field gradient and the resonance frequency inside and outside of the superconducting coil.     

HT-7U托卡马克装置中超导螺管模型磁体的设计与实验研究

介绍了 TH- 7U超导 Tokamak核聚变装置中超导螺管模型磁体的设计过程及其电磁与力学性能分析。并通过对其进行的大型超导试验获得了一些重要参数 ,这些参数的取得将对 HT-7U装置中超导磁体的工程设计具有很重要的指导意义。     

Effect of large-heat-capacity substances doping of superconducting coils on their dynamic stability

The dependence of the quench currents on the ramp rate was studied for four small NbTi coils. Two pairs of superconducting coils were tested. In one pair the SC 0.85-mm-dia wire with 2970 filaments was used, in the other two coils the SC wire contained 8910 filaments of smaller size. Two coils (with different number of filaments) contained 4.9 vol % of Large-Heat-Capacity Substance (LHCS) in the form of tiny powder evenly distributed over the winding volume, therefore their heat capacity at 4.2 K was an order of magnitude larger than that for coils without LHCS. The LHCS was introduced into the winding in a mixture with epoxy resin (“wet” winding). When the self-magnetic field varied with a rate of ≥5 T/s, premature quenches were observed in the central turns of the undoped coil made of a wire with 2970 filaments. These transitions are likely to be caused by magnetic flux jumps. In the LHCS-doped coil made of the same wire, the quenches took place at currents two to three times higher, since the sample was heated up to a critical temperature because of electrical losses (as confirmed by calculations). Thus, the improved stability of the LHCS-containing coils not only against long-term (0.1–1.0 s) disturbances but also against much shorter (10–100 μs) jumps of the magnetic flux is demonstrated.     

高分辨超导NMR谱仪的匀场

本文详细叙述了超导磁体的磁场分布和匀场线圈的设计。并对匀场电源、匀场线圈的精度和稳定性等要求作了估算。     

CRAFT TF中场线圈导体及内部接头电阻-温度特性研究

我国于2019年启动了国家大科学装置聚变堆主机关键系统综合研究设施(CRAFT)的建设,环向场(Toroidal Field, TF)线圈是聚变堆主机关键系统综合研究设施的重要组成部分.TF线圈绝缘制造采用真空压力浸渍工艺实现,因TF线圈体量巨大,为使线圈绝缘固化时温度均匀,减少绝缘树脂固化热应力,拟采用导体电流加热的方式进行加热.TF中场线圈有三个内部接头,因此需要同时知道导体和内部接头电阻与温度之间的关系,以防内部接头局部过热,导致绝缘固化失败.本文将中场内部接头样件加热到线圈绝缘工艺温度,用直流四线法测量导体和内部接头在不同温度下的电阻,得到在303～443 K温度区间内导体和内部接头电阻-温度关系式.发现相同温度下,导体电阻大于内部接头电阻,同时分析了内部接头铜套以及铬层对电阻的影响.并根据测得的电阻-温度关系式,可以得到在不同温度下超导缆及内部接头产生焦耳热的能力,从而为超导线圈绝缘固化温度控制提供重要的参考依据.     

反质子和离子加速器收集环的超导二极磁体设计

介绍了德国FAIR工程中的收集环(CR)超导二极磁体的工程设计。用CATIA软件建立了CR超导二极磁体的三维模型,并用ANSYS软件对建立的1/4模型进行了磁场和电磁力的分析,基于磁场分析对线圈盒进行了位移和应力的初步分析,并对磁体失超后液氦容器可能出现的最大位移和最大应力进行了分析。进行的分析研究为实验磁体和产品磁体的制造提供了必要的参数。     

多通道心磁系统标定方法研究

在多通道超导量子干涉器件（SQUID）磁探测系统中,磁场电压转换系数（∂ B/∂ V）是系统的一个重要参数由于SQUID器件和读出电路之间不可避免地存在差异性因此对传感器系统进行系统标定（每个通道的单独标定）显得十分重要本文采用（PCB） 板印制圆形线圈对36通道心磁系统进行标定,并与传统的亥姆霍兹方形线圈产生均匀场的标定方法进行比较结果显示PCB圆形线圈的标定结果 在1.46–1.73 pT·mV^-1 之间,亥姆霍兹方形线圈标定的结果大都在1.56–1.64 pT·mV^-1之间,结果基本一致. 关键词： 超导量子干涉器件 磁探测 磁场-电压转换系数 系统标定