一种圆鞍形磁屏蔽线圈的设计与性能研究

以毕奥-萨伐尔定律为基础,推导了一种圆鞍形线圈在空间任意点处的磁场分布表达式,优化了一种线圈结构,证明了圆鞍形线圈可以产生一定区域的稳恒磁场,并定量地给出了线圈内部磁场的空间分布情况。所设计线圈产生的磁场中,1%均匀度的磁场均匀区占轴上区域的28%,0.1%均匀度的磁场均匀区占轴上区域的10%;在1 mA的电流下,单圈线圈最大磁场补偿值为15 nT,相对偏差量不超过0.14 nT,验证了所推导表达式的正确性,为多维磁场补偿系统设计与研究提供了理论依据和参考。     

阳极磁屏蔽霍尔离子源磁场的数值模拟

为了提高离子束电流和离子束能量,进一步增加霍尔离子源的效率,对霍尔离子源阳极进行磁屏蔽,达到优化磁场位形,增强磁场对放电等离子体的约束。由磁场的数值模拟结果可知:阳极磁屏蔽后,有明显凸向阳极表面的弯曲磁场线,并且提高了磁镜磁场的磁镜比;大的正梯度磁场的存在,增强了磁场的径向分量,相对减弱了放电等离子体的震荡;不仅保留原有鞍形场的作用,而且还充分发挥了另外两个鞍形场的优势。最后通过实验结果和数值模拟结果的比较,验证了此数值模拟结果的正确性。     

鞍型和环型线圈单元偏转磁场的高次空间谐波函数

推导出了用多极场空间谐波函数表示的磁矢位的通项表达式。研究了两种典型的偏转线圈单元———鞍型线圈和环型线圈的空间偏转磁场分布函数。利用计算机代数符号推导系统 ,得到了其高次空间谐波函数 (多极场旁轴展开函数 )的解析表达式 ,为电子光学有关磁偏转系统的理论研究工作提供了有效的解析计算模型     

鞍型和环型线圈单元偏转磁场的高次空间谐波函数

推导出了用多极场空间谐波函数表示的磁矢位的通项表达式。研究了两种典型的偏转线圈单元－鞍型线圈和环型线圈的空间偏转磁场分布函数。利用计算机代数符号推导系统,得到了其高次空间谐波 函数（多极场旁轴展开函数）的解析表达式,为电子光学有关磁偏转系统的理论研究工作提供了的效的解析计算模型。     

永磁微型核磁共振成像系统匀场线圈设计研究

在核磁共振系统当中,磁场均匀性为其重要硬件参数,而有源匀场则能够精细修正磁场。本文基于永磁微型核磁共振成像系统,在确定均匀间隙情况下,开展了匀场理论分析,经模拟仿真与数值计算,设计了一套能够放置在探头屏蔽盒外侧的有源匀场系统。将此系统放置于NMI20微型核磁共振成像仪上,匀场效果从之前的10ppm提升至1.4 ppm。     

电磁微电机中平面微线圈磁场分布特性的研究

本文分析了电磁微电机中平面微线圈产生的空间磁场，把微线圈等效几何圆电流和矩形截面电流，导出了空间磁场的计算公式，接着通过四种算法的比较，建立了平面微线圈空间磁场快速准确的数值算法，最后分析了平面微线圈空间磁场的分布特性。     

电磁流量计矩形与鞍状线圈磁场的数值仿真

讨论了电磁流量计矩形和鞍状线圈所产生磁感应强度的分布情况。运用毕奥-萨伐尔定律和叠加原理,通过数值仿真得到励磁线圈在测量管道内电极横截面上的磁场分布情况。提出磁感应强度的方向平行程度和大小均匀程度2个指标,并用其来判别感应磁场分布的均匀程度。依据以上2个指标,分别对不同尺寸的矩形和鞍状励磁线圈所产生的感应磁场进行计算分析和优化。     

佳木斯篮球馆单双层鞍形组合网壳

佳木斯篮球馆是由两片单层鞍壳和两片双层鞍壳组成，其单双层鞍形网壳结构跨度均为４５ｍ，本文简要介绍该结构的设计，并分析研究了该结构的静动力特性，结果表明，该组合鞍形网壳传动路径明确，受力合理，抗震性能良好，具有较好的静力和动力稳定性。     

风驱雨荷载作用下鞍形膜结构动力响应及可靠度研究

通过有限元数值模拟和风洞试验对鞍形膜结构在风驱雨荷载作用下的动力响应及其结构可靠度进行研究。采用Workbench软件中的Mechanical APDL模块与Fluent模块建立鞍形膜结构在风驱雨荷载作用下的模型,将该模型导入ANSYS AUTODYN软件中求解得到动力响应曲线。基于气弹相似理论制作了试验模型,并对试验模型进行风驱雨动力加载试验,从而得到其膜面不同特征点在不同工况下的动力响应数据。通过蒙特卡洛法对数值模拟和试验的动力响应数据进行求解,得到鞍形膜结构的可靠指标。此外,讨论了风雨荷载组合、预张力和矢跨比对鞍形膜结构动力响应与可靠度的影响。将试验与数值模拟进行对比分析,数值模拟结果与试验结果较为吻合。研究发现：风驱雨荷载会使膜结构产生显著的非线性振动,通过增大鞍形膜结构的预张力和矢跨比可有效减小振动响应;在不同参数之间,矢跨比对膜结构可靠度的影响更为显著。论文的研究方法和结果可以为膜结构非线性动力响应研究和基于可靠度理论的膜结构设计提供参考。     

爆炸冲击载荷下耐压鞍形舱壁结构弹塑性动力屈曲

本文借助有限元软件ANSYS/LS-DYNA对耐压鞍形舱壁结构在爆炸冲击载荷作用下的弹塑性动力屈曲进行了研究。采用Budiansky-Roth屈曲准则判断鞍形舱壁的动力屈曲,研究了初始缺陷大小对鞍形舱壁结构动力屈曲的影响,并与等重量的传统三心球面舱壁结构进行了对比,然后讨论了主要设计参数对鞍形舱壁结构动力屈曲的影响。研究表明：鞍形舱壁结构比等重量的三心球面舱壁结构动力屈曲载荷有明显提高,且对初始缺陷不敏感,合理的匹配各设计参数可以使舱壁结构的动力屈曲性能达到最佳。     

多圈共轴线圈产生错位对激励磁场的影响

研究了多圈共轴线圈产生错位情况下其在空间激励磁场的分布变化,用最基本的毕奥-萨伐尔定律和叠加定理推算出磁场公式,并借助MATLAB软件计算出磁感应强度变化的数值解,绘制出线圈轴上和中心平面上的磁场变化分布图等。由此判断出磁感应线圈缠绕规则性对激励磁场分布的影响,对于一定精度磁场的产生给出合理的理论建议。计算结果表明,线圈偏移量与平均半径比值不大于0.04时,轴上磁感应强度变化在10-11T量级,中心平面上磁场相对变化不超过1%。     

Magnetic Field Stabilization for Magnetically Shielded Volumes by External Field Coils

For highly sensitive magnetic measurements, e.g., a measurement of the neutron electric dipole moment (EDM), the magnetic field has to be stable in time on a level below picoTesla. One of several measures we employ to achieve this uses an external field coil system which can stabilize the ambient external field at a predefined value. Here we report on the construction and characterization of such a system in the magnetic test facility at PSI. The system actively stabilizes the field along the axis of the EDM experiment by means of four coils in a Helmholtz-like configuration. Additional coils serve to compensate for transverse ambient field components. Because of the long integration times in the EDM experiment (about 100 s or more) only slow disturbances have to be corrected for. The performance of the system has been measured using static and moving magnetic sources and suppression factors in excess of 200 have been observed.     

经穴磁刺激线圈优化设计与仿真

经穴磁刺激与传统针灸、电刺激相比具有无创伤、无不适感、易重复和进行深部刺激等独特优点.磁刺激系统中载流线圈设计对磁场强度和磁场分布具有重要作用.在理论分析载流线圈磁场分布基础上,设计了不同8字形和碗状结构磁刺激线圈,并采用Ansys有限元分析软件对线圈沿径向和轴向产生的磁场分布进行仿真,研究8字形和碗状结构线圈的磁场聚焦性和刺激深度.结果表明,碗状线圈具有较好的磁场聚焦性且有一定的刺激深度,在皮层下1.5～2 cm左右仍有3～10 mT的磁场强度.同时获得了适合于经穴磁刺激系统的最佳线圈形状和参数,为穴位磁刺激技术应用于临床治疗奠定了良好基础.     

A potential vector field solution in superconducting magnets, part I: Method of calculation

An analytical method is presented for calculating values and distribution of the magnetic field in superconducting dc magnets composed of cylindrical or saddle type coils in cylindrical symmetry. The method takes into account the actual length and finite thickness of the coils as well the presence of radial and axial ferromagnetic yokes. The magnetic field is determined by carrying on an expansion of the current density distribution of the coils with Fourier series: for each term of the expansion, the corresponding components of the flux density are obtained by means of the calculation of the magnetic potential vector. The resultant magnetic field is determined by applying the principle of superposition of the effects by summing up the harmonic fields; as the magnet contains ferromagnetic materials, one or more suitable constant values of permeability for such materials must be chosen.     

Simulation of the Magnetic Induction Vector of a Magnetic Core to be Used in FFC NMR Relaxometry

This paper is a contribution for the assessment and comparison of magnet properties based on magnetic field characteristics particularly concerning the magnetic induction uniformity in the air gaps. For this aim, a solver was developed and implemented to determine the magnetic field of a magnetic core to be used in Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry. The electromagnetic field computation is based on a 2D finite-element method (FEM) using both the scalar and the vector potential formulation. Results for the magnetic field lines and the magnetic induction vector in the air gap are presented. The target magnetic induction is 0.2 T, which is a typical requirement of the FFC NMR technique, which can be achieved with a magnetic core based on permanent magnets or coils. In addition, this application requires high magnetic induction uniformity. To achieve this goal, a solution including superconducting pieces is analyzed. Results are compared with a different FEM program.     

非晶丝微磁化线圈磁电阻抗效应研究

本文研究了铁基及钴基非晶态合金丝在由微磁经线圈所产生的轴向交变磁场的作用下所呈现的磁电阻抗效应，经出了一些测试结果，结果表明，微磁化线圈两端的电压信号峰－峰值随轴向外磁场Ｈｅ的增加而单调减少，钴基非晶丝可呈现巨磁电阻抗效应，利用该效应可制成新型磁敏元件及器件。     

Magnet system optimization for two uniform field coils supplied bymains and capacitor banks

Physical experiments often require a short-term magnetic field with a specified uniformity to be created in a certain space. In this case, various electric energy storage systems are used for the pulse supply of magnet systems, for example, a bank of capacitors. The simplest configuration of such a magnet system is formed by two identical coils. This paper presents the methods and main results of a two coils system optimization taking into account the field uniformity and other requirements when this system is supplied either by mains or by capacitor banks     

The Specific Load Capacity of Radial-Flux Radial Magnetic Bearings

This paper addresses the specific load capacity of radial-flux radial magnetic bearings and provides some insight into what values are achievable and how these values depend on various parameters such as air-gap thickness, allowable temperature rise in the coils, certain heat-transfer coefficients, and certain de-rating factors associated with the distribution of the bearing load in time and space. We define the specific load capacity of a radial magnetic bearing as the ratio of the largest sustainable root-mean-square radial force to the total self-weight of all parts necessary for the electromagnetic function of the bearing. We show that it is possible to push the limit of the specific load capacity of naturally cooled bearings up to around 35:1 with present-day materials, for a wide range of practical bearing sizes. This figure is still very small compared with the capacity of mechanical bearings.