FE Stress Analysis of the Toroidal Field Magnets of HT-7U

In this paper, the mechanical strength of the toroidal field (TF) magnets of HT-7U with the electromagnetic force in different magnetic fields is emphatically analyzed by means of finite element method. The model and feasible method of computation are put forward. Some important conclusions are made available for reference in the design and construction of TF for HT-7U.

Numerical study of fast ion behavior in the presence of magnetic islands and toroidal field ripple in the EAST tokamak

A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.

The Analysis and Calculation for the Toroidal Magnetic Field of HT-7U

The HT-7U super-conducting tokamak is a full super-conducting magnetically confined fusion device, It mainly consists of super-conducting toroidal field (TF) coils and super conducting poloidal field (PF) coils. This paper describes the distribution of magnetic field, ripple and electromagnetic loads of TF system, some results are necessary to analyze and calculate the stresses and deformation on TF system by a finite element method. Meanwhile, in this paper, the main scope of the calculation is carried out for the case of constant magnetic field on conductor of the TF coil winding in order to provide electromagnet parameters for the quench analysis of Cable-in-Conduit Conductor (CICC) of TF system in HT-7U.

Preliminary Engineering Design of Toroidal Field Magnet System for Superconducting Tokamak HT-7U

HT7U is a large fusion experimental device. It will be built in the Institute of Plasma Physics of Chinese Academy of Sciences. The mission of HT-7U is to develop the scientific basis for a continuously operating tokama-k fusion reactor. This paper describes only a toroidal field (TF) superconducting magnet system of HT7U. In this paper, design criteria of conductor and stability analysis, coil winding and support structure design of magnet system, mechanical calculation and stress analysis, heat load evaluation are given.

The effect of toroidal field on the rotating magnetic field current drive in rotamak plasmas

A rotamak is one kind of compact spherically shaped magnetic-confinement device. In a rotamak the plasma current is driven by means of rotating magnetic field （RMF）. The driven current can reverse the original equilibrium field and generate a field-reversed-configuration. In a conventional rotamak, a toroidal field （TF） is not necessary for the RMF to drive plasma current, but it was found that the present of an additional TF can influence the RMF current drive. In this paper the effect of TF on the RMF current drive in a rotamak are investigated in some detail. The experimental results show that addition of TF increases the RMF driven current greatly and enhances the RMF penetration dramatically. Without TF, the RMF can only penetrate into plasma in the edge region. When a TF is added, the RMF can reach almost the whole plasma region. This is an optimal strength of toroidal magnetic field for getting maximum plasma current when Bv and radio frequency generator power are fixed. Besides driving current, the RMF generates high harmonic fields in rotamak plasma. The effect of TF on the harmonic field spectra are also reported.

Design of a Wedge-Shaped Toroidal Field Winding for KTX Device

The KTX device is a reversed field pinch （RFP） device currently under construction. Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms. Its major radius is 1.4 m and its minor radius is 0.55 m. One of the most important problems in the magnet system design is how to reduce the TF magnetic field ripple and error field. A new wedge- shaped TF coil is put forward for the KTX device and its electromagnetic properties are compared with those of rectangular-shaped TF coils. The error field B,I/Bt of wedge-shaped TF coils with 6.4 degrees is about 6% as compared with 8% in the case of a rectangular-shaped TF coil. Besides, the wedge-shaped TF coils have a lower magnetic field ripple at the edge of the plasma region, which is smaller than 7.5% at R=1.83 m and 2% at R=l.07 m. This means that the tokamak operation mode may be feasible for this device when the plasma area becomes smaller, because the maximum ripple in the plasma area of the tokamak model is always required to be smaller than 0.4%. Detailed analysis of the results shows that the structure of the wedged-shape TF coil is reliable. It can serve as a reference for TF coil design of small aspect ratio RFPs or similar torus devices.

A Consideration on Increasing Current Density in Normal Conducting Toroidal Field Coil for Spherical Tokamak Power Plant

The center post is the most critical component as an inboard part of the toroidal field coil for the low aspect ratio tokamak. During the discharge it endures not only a tremendous ohmic heating owing to its carrying a rather high current but also a large nuclear heating and irradiation owing to the plasma operation. All the severe operating conditions, including the structure stress intensity and the stability of the structure, largely limit the maximum allowable current density. But in order to contain a very high dense plasma, it is hoped that the fusion power plant system can operate with a much high maximum magnetic field BT ≥12 T-15 T in the center post. A new method is presented in this paper to improve the maximum magnetic field up to 17 T and to investigate the possibility of the normal conducting center post to be used in the future fusion tokamak power plant.

The Implementation of Magnetic Islands in Gyrokinetic Toroidal Code

The implementation of magnetic islands in gyrokinetic simulation has been verified in the gyrokinetic toroidal code（GTC）.The ion and electron density profiles become partially flattened inside the islands.The density profile at the low field side is less flattened than that at the high field side due to toroidally trapped particles in the low field side,which do not move along the perturbed magnetic field lines.When the fraction of trapped particles decreases,the density profile at the low field becomes more flattened.

Radial magnetic field in magnetic confinement device

The intrinsic radial magnetic field（B r） in a tokamak is explored by the solution of the Grad–Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement.

基于环形均匀磁场的磨粒传感器设计

针对传统的电感式磨粒传感器流量较小、监测区域磁感应强度较低、梯度较大的问题,设计了一种基于环形均匀磁场的磨粒传感器。通过设计环形流道,实现在监测区域内产生均匀径向磁场。同时分析了磁路截面面积与传感器磁感应强度的关系,并比较不同磁极截面形状对磁感应强度的影响,完成了对传感器的结构优化,得出采用楔形磁极可有效提高磁场利用率。利用Ansys软件建立传感器的三维有限元模型,揭示了传感器的静磁场和瞬态特性。利用单磨粒无油液实验,对比分析实验结果与仿真结构的输出特性,验证了传感器的有效性。实验结果表明,传感器在采用低倍率放大器的情况下,可检测出0.28 mm的铁磁性磨粒,与现有的传感器相比具有较高的灵敏度。

强磁场托卡马克环向场线圈应力缓解研究

针对强磁场托卡马克环向场(TF)线圈应力过大、结构材料难以承受的问题,根据静水应力原理分析了通过外部承压结构来降低TF线圈内腿应力的有效性。采用COMSOL有限元软件开展模拟,研究了液氮冷却强磁场铜导体托卡马克外部承压结构在不同厚度下TF线圈磁体应力的降低程度;对比了铍铜合金和无氧铜作为导体材料所需要的外部承压结构的厚度和体积。

高速高功率密度无轴承永磁薄片电机设计与优化

传统无轴承电机在高速和高功率密度之间难以取得平衡,为此围绕高速高功率密度无轴承永磁薄片电机,对其拓扑结构、绕组形式、主要尺寸等方面进行优化设计,在保证转速和功率密度的基础上有效地提升悬浮性能。通过对运行工况的分析,得出电机拓扑结构需具备的基本特点,提出一种采用环形集成绕组的表贴式无轴承永磁薄片电机。在兼顾转矩和悬浮力输出性能、机械防护可靠性的基础上,对电机的电磁气隙长度和永磁体参数等主要尺寸进行优化设计。针对电机饱和、绕组端部伸出等不利因素,分别采取了超前角弱磁、定子略长的性能提升策略,有效地避免了悬浮力的大幅度跌落。搭建20 000 r/min的无轴承永磁薄片电机有限元仿真模型并制造实物样机。通过对电磁转矩和主、被动悬浮力的分析,证明了本文设计的无轴承永磁薄片电机兼具良好的转矩与悬浮力输出性能,单位幅值电流产生的电磁转矩、主动悬浮力分别为0.166 N·m、4.4 N,电机输出功率10 kW、功率密度5.2 kW/kg。

基于超级电容器的核聚变磁体电源系统环形场线圈电源设计

[目的]研究旨在为核聚变磁体电源系统中的环形场线圈开发一种高效可靠的脉冲电源系统。针对核聚变装置在高功率需求下的挑战,提出了一种基于超级电容器的电源解决方案,旨在增强能量存储的效率和系统的稳定性。[方法]通过采用模块化多级转换器技术,开发了一种新型的脉冲电源结构。利用超级电容器的高功率密度和快速充放电能力,作为主要的能量存储单元,以满足环形场线圈的高频脉冲运行需求。此外,探讨了超级电容器与模块化多级转换器技术结合的优势,如系统的灵活性和可扩展性。[结果]研究结果显示,所开发的电源系统能够有效支持核聚变反应堆的脉冲操作需求,确保了能量的高效输送和转换。[结论]基于超级电容器的脉冲电源系统为核聚变装置提供了一种有效的能量解决方案。该系统不仅提高了能量转换的效率,也增强了整个设备的运行稳定性和可靠性。未来的研究将进一步优化电源结构和性能,以适应更广泛的应用场景。

基于霍尔元件的螺线环磁场测量装置及实验设计

根据“新工科”背景下大学物理实验教学的改革需求和霍尔元件发展的新趋势,研制了螺线环磁场测量装置,装置由自制的磁场测试仪、霍尔元件尺、移动导轨和螺线环组成。通过给螺线环通入直流励磁电流(强度可调),使螺线环内部产生稳定的磁场,使用自行设计的霍尔元件移动尺可测量螺线环磁感应强度与励磁电流、环路半径之间的关系,还可以测量螺线环的磁场分布和空气磁导率。相应的实验设计可以帮助学生直观地认识螺线环磁场的分布规律,理解霍尔效应测量磁场的基本原理,深化学生对磁场相关理论的理解,同时促进理论学习与工程应用的融合,培养并锻炼学生分析解决实际工程问题的能力。

螺绕环磁场的镜像对称性分析

利用安培环路定理求解长直导线、长直螺线管、螺绕环等载流系统的磁场时,对称性分析是选取闭合回路的关键.通过分析解螺绕环磁场时的镜像对称条件,说明合理应用对称性分析,能够使求解电场和磁场问题的图像更清晰、计算更简化、表述更准确.因此,在电磁学教学中应给予对称性分析足够的重视.

变压器环形铁芯建模和剩磁测量

大型电力变压器进行空载合闸操作时,铁芯中的剩磁可能会引起励磁涌流,导致变压器无法正常投入运行。文章介绍了一种新的分析和测量剩磁的方法,该方法是在外加正反向直流电压激励的基础上实现的。通过分析剩磁产生的原理,建立了基于Jiles-Atherton磁滞理论模型的变压器环形铁芯仿真模型。在环形铁芯绕组上先后施加大小相等方向相反的直流电压,可以得到两个不同的响应电流,结合场路暂态分析,可以判断剩磁的方向,并且找到响应电流和剩磁之间的关系。该方法可以在对变压器铁芯中原有剩磁影响不大的情况下准确测量剩磁的大小和方向。通过自主搭建的实验平台对环形铁芯中的剩磁进行了测量,验证了仿真结果的合理性。

EAST纵场磁体系统16kA高温超导电流引线的研究

在全超导磁约束核聚变装置EAST中,采用高温超导电流引线将处于室温的电源连接处于超临界氦温区的超导磁体上。为降低实验过程中的运行成本,EAST装置中纵场磁体的电流引线采用混合式结构。电流引线测试结果表明引线符合设计要求。

3MV感应电压叠加器的磁感应腔研制

根据脉冲驱动源和负载参数,提出了3 MV感应电压叠加器磁感应腔的设计指标为1.2 MV/70ns。由感应腔的电流传输效率和真空同轴线绝缘要求,确定了磁芯的几何尺寸;研制了矩形比为0.5的预退火非晶磁环,明确磁环数量不少于6只;在30 T/s时,实验测量的最大脉冲相对磁导率与饱和波模型计算结果相当;估算磁感应腔的等效激磁电感约为7.3μH,涡流损耗电阻约为139Ω。根据临界击穿场强的经验公式,采用电场数值分析方法,确定了磁感应腔的电气结构;实验验证了磁感应腔设计有效性;建立了基于磁感应腔的3 MV感应电压叠加器全电路模型,阳极杆箍缩二极管电压、电流计算波形,与实验结果基本相符。

机电集成超环面传动的驱动原理

机电集成超环面传动是一种新型传动机构,阐述了机电集成超环面传动的集成原理,根据坐标变换原理,推导了蜗杆齿槽的空间曲线,给出了蜗杆与行星轮正确啮合所满足的关系,介绍了环面蜗杆的加工轨迹和绕线方式,并对蜗杆旋转螺旋磁场的产生及控制进行了简要说明。研究结果对于该系统的研究与制造,具有一定的参考价值。

基于环形绕组的异步电机极-相调制方法

针对异步电机变频调速时铁心损耗偏大、匝间绝缘易老化而变极调速中绕组浪费、需断电变极等问题,提出基于环形绕组的异步电机极相调制方法。对环形绕组电机和极相调制方法进行分析,并对环形绕组电机在采用极相调制时的定子磁场进行解析计算与有限元仿真,以证明其定子磁场建立的可行性。仿真结果表明:该方法能够克服变频与变极调速系统的各自缺点,可使电机在不断电的情况下实现极数与相数的改变,使得电机能够提供更大的输出转矩,并减少了在极对数较少时电机的振动和定子磁场谐波。同时,环形绕组异步电机的结构较笼型异步电机的结构具有更好的散热性及较低的维修成本。