基于有限元法对亥姆霍兹线圈磁场的分析

为进一步明确亥姆霍兹线圈所产生磁场的近场特性,尝试采用基于有限元方法的ANSYS软件对亥姆霍兹线圈进行分析.采用ANSYS软件对亥姆霍兹线圈建立三维实体有限元模型并进行仿真.仿真结果与Matlab语言绘制亥姆霍兹线圈磁感应强度的空间分布图相比较,结果说明ANSYS有限元模型优于Matlab语言.最后通过实验验证所建的三维亥姆霍兹线圈有限元模型的有效性和正确性,对研究亥姆霍兹线圈其他性质有一定的参考应用价值.     

方形亥姆霍兹线圈磁场系统均匀性分析

方形亥姆霍兹线圈用于模拟零磁场或量程范围内的任意大小和方向的磁场,其磁场均匀区与线圈结构尺寸有关。为了得到其磁场均匀区与结构尺寸的关系,构建了方形亥姆霍兹线圈的数学模型,导出了线圈内部任意点的磁感应强度矢量表达式,得出了输出电流与产生磁场大小的对应关系,利用程控恒流源和磁强计跟踪补偿动态地模拟出稳恒磁场,对系统产生的磁场的均匀区进行了测定,分析表明,理论计算与实验结果有较好的一致性。     

亥姆霍兹线圈场均匀性的仿真研究

通过对亥姆霍兹线圈内部的均匀场进行仿真计算,直观地看到了线圈内部场的变化趋势,将结果与解析法结果对比,误差在1％左右,亥姆霍兹线圈在其轴线附近产生的磁场均匀度较好。并以r为200mm、250mm、300mm为例,仿真计算出均匀区的大小,结果表明,线圈馈人点的位置会影响均匀场对称中心的位置。     

基于COMSOL软件仿真亥姆霍兹线圈

本文通过应用COMSOL有限元软件对亥姆霍兹线圈产生的涡流进行仿真分析,应用软件自带的后处理功能,图像化的分析亥姆霍兹线圈产生的电磁场响应特性。     

地磁匹配导航半实物仿真方案设计及关键技术分析

以地磁匹配导航原理为理论依据,设计了半实物仿真系统的总体方案。在半实物仿真模型选取和结构组成的基础上,系统分析地磁场数据库仿真、载体干扰磁场补偿、地磁场环境仿真和地磁匹配导航算法这4种关键技术并提出了相应的工程解决方案,为实现地磁匹配导航半实物仿真提供一种参考。     

亥姆霍兹磁场分布演示仪的设计与实现

亥姆霍兹线圈是一对匝数和半径相同的共轴平行放置的圆线圈,两线圈间的距离等于线圈半径。亥姆霍兹磁场分布演示仪是利用单片机技术将霍尔探头检测到的磁场信号显示到点阵屏上,移动探头就可以将磁场分布情况以曲线的形式显示出来。该仪器主要服务于实验教学,生动立体的演示给教学带来了很好的效果。     

永磁体双磁环结构的磁场均匀性分析

提出了可用于四频差动激光陀螺法拉第室的永磁体双磁环结构,用以产生较强且均匀的轴向磁场.推导了永磁体磁环轴线上磁场分布的解析式,理论并实验证明了该解析式的正确性.引入磁场均匀度概念,提出了类亥姆霍兹线圈的舣磁环结构,模拟了磁环间距对磁场分布的影响,数值计算了不同均匀度下双磁环结构的磁场分布特征.在此基础上,针对四频差动激光陀螺法拉第室的要求,给出了适用的设计方案.     

均匀磁场与双频激光器的差频特性

磁场均匀性影响双频激光器的差频特性及输出光束的圆偏振度。采用简化物理模型,设计出最佳参数的同轴腰鼓形磁钢,获得了不均匀性小于1.3%的轴向磁场,此设计也可用于行波管等的聚焦场中。新颖的轴对称线圈磁场设计获得了不均匀性小于0.5%的可调场,其单位场强的激磁安匝数、场均匀性、平衡温升等指标均优于长螺线管或亥姆霍兹线圈。实验测量     

利用MATLAB模拟亥姆霍兹线圈磁场分布

文章主要讨论亥姆霍兹线圈中磁场的分布情况,通过MATLAB模拟得到磁场分布的理论图形,并与实际测得值比较进行误差分析,通过实验数据的计算比较,证明磁场满足迭加原理,通过MATLAB的编程过程进一步加深对毕奥-萨伐尔定律的理解.通过该实验的操作、数据处理、计算机模拟、画图对比等过程更好地理解电和磁的相互作用问题.     

一种电磁式声能收集器的设计

基于电磁感应和亥姆霍兹共振原理设计一种电磁声能收集器,通过声-力-电转换的理论研究和实验测试证明装置能够有效地将声能转换为电能。声能收集器由亥姆霍兹共振器和电磁换能器耦合而成,当入射声波频率与声能收集器共振频率一致,声压被亥姆霍兹共振器放大,同时声能收集器输出电压也达到最大。模拟和实验结果表明,当声能收集器工作于共振频率时,输出的电压值最大,并且输出电压与输入声压成正比。     

Wide Field Magnetic Luminescence Imaging

This study demonstrates how magnetic‐field‐dependent luminescence from organic films can be used to image the magnetic configuration of an underlying sample. The organic semiconductors tetracene and rubrene exhibit singlet exciton fission, which is a process sensitive to magnetic fields. Here, thin films of these materials were characterized using photoluminescence spectrometry, atomic force microscopy, and photoluminescence magnetometry. The luminescence from these substrate‐bound thin films is imaged to reveal the magnetic configuration of underlying Nd‐Fe‐B magnets. The tendency of rubrene to form amorphous films and produce large changes in photoluminescence under an applied magnetic field makes it more appropriate for magnetic field imaging than tetracene. This demonstration can be extended in the future to allow simple microscopic imaging of magnetic structure.     

磁场中硅熔体的磁黏度

利用魔环磁场,对硅熔体施加横向可调的磁场.采用回转振荡法,测量了硅熔体在不同温度、不同水平方向磁场下的磁黏度.研究结果表明,引入磁场,使硅熔体的磁黏度增加,且磁黏度与磁场强度呈抛物线关系.     

磁场中硅熔体的磁黏度

利用魔环磁场,对硅熔体施加横向可调的磁场.采用回转振荡法,测量了硅熔体在不同温度、不同水平方向磁场下的磁黏度.研究结果表明,引入磁场,使硅熔体的磁黏度增加,且磁黏度与磁场强度呈抛物线关系.     

Magnetic Field Converters Based on the Spin-Tunnel Magnetic Resistance Effect

Russian Microelectronics - The modern designs of magnetic field transducers (MFTs) based on nanostructures with the spin-tunnel magnetoresistive effect (STMR) and the main areas of their...     

RKA 引导磁场设计研究

本文为RKA 设计了一套秒级脉冲磁场系统,该系统主要由磁场线圈和磁场电源两部分组成,磁场线圈通过迭代 获得所需截面形状,之后进行了必要的电磁参数设计,对与之配套的磁场电源提出了主要技术要求和时序控制问题。最 后初步测试了RKA 磁场位形情况,经测试,该秒级脉冲磁场性能稳定,满足RKA 磁场约束要求。     

双光纤布拉格光栅磁场传感器

载流导线在磁场中产生的电磁力使等腰三角形悬臂梁变形,从而导致安装在悬臂梁两边的光纤布拉格光栅(FBG)的布拉格波长漂移.通过检测2个FBG的波长漂移差,得到被测磁场的磁感应强度.双FBG通过补偿温度效应,解决了FBG传感器的交叉敏感问题.垂直放置的等腰三角形悬臂梁,确保FBG在传感过程中不出现啁啾现象,又避免了自身重量和导线重量对测量结果的影响,从而减少了测量误差.该系统传感灵敏度为1.11 nm/T,与理论值的相对误差为4.31%,结果表明,该传感器结构是可行的.     

Magnetic Field Coils for Gradiometer Balancing

We present a design of a compact set of biplanar coils which produces magnetic fields of eight different profiles for the purpose of gradiometer balancing. The magnetic field profiles correspond to uniform magnetic fields in three orthogonal directions and five linearly independent first-order gradients. The coils are made by etching square printed circuit boards that have dimensions of 0.5 m times 0.5 m. The typical inhomogeneity of the magnetic fields and gradients produced by the ideally assembled coil set in a cylindrically shaped volume that measures 50 mm in diameter and 225 mm in height is of the order of 10 ^-5. The coils yield uniform fields and first-order gradients of at least 1(muT/A) and 1(muT/Amiddotm), respectively. The influence of manufacturing tolerances on the performance of the set is investigated by means of Monte Carlo simulations. Based on these simulations, we concluded that the coil set needs to be assembled with a tolerance of 0.1 mm in order to reach a required uniformity of order of 10^-5-10^-4     

The AMPTE CCE Magnetic Field Experiment

The AMPTE CCE spacecraft carries a high-resolution Magnetic Field Experiment for the operational purpose of determining spacecraft attitude and to fulfill the scientific objectives of providing magnetic-field measurements necessary for the determination of particle pitch angles, identification of geospace boundaries, measurement of geomagnetic activity, and the study of magnetospheric current systems and plasma processes. This experiment includes a fluxgate-magnetometer system with the sensors mounted on a 2.3-m boom to reduce spacecraft-related measurement errors. Te experiment has 7 automatically switchable ranges from ±16 to ±65 536 nT (full scale) and resolutions commensurate with a 13-bit A/D converter in each range (±0.002-±8 nT). Approximately 8.6 vector-samples/s are acquired, with information on fluctuating fields in the 5-50-Hz range provided by a system of filters and peak detectors. This instrument was operated from the time of the launch of the CCE spacecraft and is presently working in all modes as designed. The details of this experiment and early data are presented in this paper.     

微波炉炉腔内电磁场仿真

利用高频电磁场软件对微波炉建模,设置腔体内的介质材料的电特性参数,仿真得到的反射系数和相位图与矢量网络分析仪实测值比较,误差小于8%,吻合较好,证明本方法是有实用价值.还对该方法进行了误差分析和讨论.进而研究波导管与腔体相对位置对微波炉匹配性能的影响.这些对微波炉开发工程师在微波炉冷匹配时提供理论指导,缩短了微波炉新平台开发时间,提高了竞争力.