双线并绕螺线管引入霍尔效应测量螺线管磁场的实验改进

针对大学物理实验中霍尔效应测量螺线管磁场实验中同一螺线管所通入电流既作为已知电流求霍尔元件的灵敏度又作为未知电流求螺线管的磁场这一不足,提出一种设计方法,采用双线并绕螺线管使两个电流进行有效区分,同时还可以测量螺线管内的叠加磁场,可使学生深刻全面理解霍尔效应测量螺线管磁场的原理及螺线管磁场的性质,并可作为设计性实验项目培养学生的创新意识。     

设计一种霍尔元件的保护装置

1引言 大学物理实验中，“用霍尔效应法测量磁场”实验是工科各专业必做的实验之一，笔者已给学生上这个实验许多年，深感这个实验装置必须改进；因为在实验中，虽然笔者再三强调不要把励磁电流接至霍尔元件上，仍然有部分学生因接错线路而导致霍尔元件被烧毁．由于上大学物理实验课的学生多，仪器的使用率特别高，所以一个学期下来总有六七台甚至更多台霍尔效应实验仪中的霍尔元件被烧毁而需更换．     

利用霍尔元件测永磁材料的静态特征

利用霍尔元件测永磁材料的静态特征石环英，石琳（长沙铁道学院４１００７５）（湖南大学）在大学物理实验中有一利用霍尔效应测永磁材料磁场的实验，测量Ｃ型电磁铁空隙中的磁感应强度．本人以此实验为基础，设计了一种利用霍尔元件测永磁材料静态磁特性的设备．一、实验...     

利用双霍尔探头测螺线管中低频交变磁场

在霍尔效应实验中利用双霍尔探头测磁场,通过对磁场定标,研究了螺线管中低频交变磁场,并分析了螺线管中低频交变磁场的分布特征,为学生测量低频弱电磁辐射提供了新的思路.     

设计一种霍尔元件的保护装置

大学物理实验中，“用霍尔效应法测量磁场”实验是工科各专业必做的实验之一，由于学生因接错线路而导致霍尔元件被烧毁．一个学期下来总得有六七台甚至更多．为改进这个实验装置，通过研究，如果在霍尔元件电流输入端和电压输出端各串联一个额定电流为32mA的保险丝就能达到这个目的．     

基于素质培养的霍尔效应实验

本文通过对大学物理实验中霍尔效应实验的教育目标设计,说明大学物理实验如何在培养学生科学素质上所发挥的作用.     

集成霍尔传感器特性测量与应用实验的改进

对大学物理实验中集成霍尔传感器特性测量与应用实验的进行了改进.提出了用专门的螺线管测量灵敏度,使用2片正交放置的霍尔片测量待测通电螺线管中磁场磁感应强度,并给出了具体的测量步骤和电路设计以及测量结果.     

基于霍尔效应的称重装置设计与研究

霍尔传感器被广泛应用于各个领域中,它是一种磁电式传感元件,利用霍尔效应原理可以测量时间、位移、速度、磁场强度等物理量。基于霍尔效应设计并研究的称重装置,是本科生大学物理创新实验中的一种新想法。首先设计并搭建了硬件平台,通过实验测得数据并验证了其正确性。     

HL-5霍尔效应测试仪测量滋场曲线存在畸变的分析

在利用HL-5霍尔效应测试仪测量磁场的实验中,发现有些仪器的测量曲线在磁极边缘附近存在畸变．通过磁极表面与磁极之间磁场分布的测量和磁极间磁场的分布规律的计算,分析了曲线产生畸变的原因．     

霍尔元件线度对磁场测量影响的研究

在原有霍尔效应原理的基础上,利用微积分的基本方法和相关的物理知识推导非均匀磁场中利用霍尔效应测量磁场的理论公式,并结合该公式理论解释实验中对于霍尔元件线度的要求,以及说明非均匀磁场的测量对霍尔元件线度的要求,从而说明实验中经常遇到的一类问题——平均值问题。     

磁场梯度对Hall推力器放电特性影响的实验研究

为进一步探索Hall推力器通道内磁场优化设计理论,通过实验分析了强场区磁场梯度对推进剂的电离与加速等放电过程的影响. 研究发现,在本实验设计的磁场梯度范围内,磁场梯度大小对推进剂的电离过程影响较小,但是对离子流的加速特性会产生较为明显的影响.随着磁场梯度的增加,离子束的能量分布会趋于集中,推力器效率提高. 最后,对磁场轴向梯度进一步变大可能会引起的一系列物理问题如有限Larmor半径效应、电子传导机理转变规律和梯度漂移效应等进行了分析和思考.     

霍尔效应法测量通电双圆线圈磁场的数据处理

介绍了霍尔效应实验原理,对实验数据进行曲线拟合,得出了通电双圆线圈内磁场的分布,并计算了霍尔元件的霍尔灵敏度。     

The spectrometer for the GunLab experiment

The spectrometer for the GunLab experiment is described. This spectrometer incorporates a dipole magnet, a fluorescent screen, and a CCD camera and is designed to measure the momentum of electron beams in the range of 1–10 MeV/c with a resolution of 0.1%. If a transversely deflecting RF cavity is installed in front of the dipole magnet, one may investigate the longitudinal phase portrait of a beam. The spectrometer is distinctive in that a Hall sensor is placed in the magnetic field of the dipole magnet. This sensor allows one to accurately measure the magnetic field and, consequently, the momentum of an electron beam.     

Aharanov-Bohm interference and fractional statistics in a quantum Hall interferometer

We compute the temperature, voltage, and magnetic field dependences of the conductance oscillations of a model interferometer designed to measure the fractional statistics of the quasiparticles in the fractional quantum Hall effect. The geometry is the same as that used in recent experiments. With appropriate assumptions concerning the relative areas of the inner and outer rings of the interferometer, we find the theoretical results, including the existence of super periodic Aharonov-Bohm oscillations, to be in remarkably good agreement with experiment. We then make additional experimental predictions with no adjustable parameters which, if verified, would confirm the proposed interpretation of the experiment as a measurement of fractional statistics.     

L波段同轴相对论返波振荡器导引磁场设计

设计了一个用于为L波段同轴相对论返波振荡器提供导引磁场的双线绕制、分段磁场线圈系统。根据粒子模拟中对磁场的要求和实验室已有的条件来确定磁场的各参数,通过数学软件Mathcad和全电磁粒子模拟程序Karat对设计出的轴向磁场位形进行验证。采用基于Hall效应的Tesla计对加工好的磁场线圈产生轴向磁场空间分布进行了测量,同时利用电子束轰击尼龙靶来考察电子束被导引的效果。利用绕制好的磁场线圈开展了初步实验研究,在二极管电压655kV,电子束流为10.4kA,导引磁场0.7T的条件下,输出微波峰值功率约为864MW,微波波形半高宽为23ns,功率转换效率约为12.7%,频率1.61GHz。     

Estimating the sizes of surface cracks based on Hall element measurements of the leakage magnetic field and a dipole model of a crack

A method is proposed for estimating the sizes of surface cracks in magnetic materials. The method is based on applying a magnetic field, then determining the leakage magnetic field in the vicinity of a crack by moving a Hall element on the surface of the material along one or two scanning lines crossing the crack, and measuring the corresponding Hall voltage distribution. A dipole model of a crack is utilized, in which a surface crack is considered as being full of magnetic dipoles aligned parallel to the applied field, and whose density varies linearly along the depth of the crack. Analytical expressions are derived for the z-component of the intensity of the leakage magnetic field, and for the measured Hall voltage in the vicinity of a crack with an arbitrary cross-section along its long axis when it is perpendicular to the applied field. The crack sizes and the parameters of the distribution of magnetic dipoles along the crack depth are computed by crack inversion, which represents a regression for the Hall voltage distribution. A variable theoretical Hall voltage distribution is fitted to the measured Hall voltage distribution by minimizing the corresponding RMS error, which gives the unknown parameters at the end of the minimization. Hall voltage distributions are measured on ferromagnetic steel samples containing one artificial surface crack. Some crack inversions are performed for estimating the maximum crack depth and the crack width of cracks with rectangular and isosceles triangular cross-sections along the long crack axis. The accuracy of these crack inversions increases by utilizing either Hall voltage distributions measured along only one of the scanning lines, instead of along both scanning lines, or by using more precisely measured Hall voltage distributions. The fast and accurate estimation of the maximum crack depth and the crack width by such crack inversions could be important for pipeline inspection. Other crack inversions are performed for determining the cross-section along the long axis of the investigated cracks with satisfactory results. Received: 2 March 2001 / Accepted: 10 April 2001 / Published online: 25 July 2001     

A Hall effect angle detector for solid-state NMR

We describe a new method for independent monitoring of the angle between the spinning axis and the magnetic field in solid-state NMR. A Hall effect magnetic flux sensor is fixed to the spinning housing, so that a change in the stator orientation leads to a change in the angle between the Hall plane and the static magnetic field. This leads to a change in the Hall voltage generated by the sensor when an electric current is passed through it. The Hall voltage may be measured externally by a precision voltmeter, allowing the spinning angle to be measured non-mechanically and independent of the NMR experiment. If the Hall sensor is mounted so that the magnetic field is approximately parallel to the Hall plane, the Hall voltage becomes highly sensitive to the stator orientation. The current angular accuracy is around 10 millidegrees. The precautions needed to achieve higher angular accuracy are described.     

结合位移变化的磁场测定装置的设计及应用

利用PASCO公司生产的磁场传感器与运动传感器,设计了结合位移变化的磁场测定装置,该装置中添加了自行设计的反射板,使该装置可以在一定距离范围内连续地实时地测量某一区域内的磁场分布情况,并成功将该套装置应用到红豆生长的磁场生物效应实验中。利用该装置测量了红豆生长培养槽中的磁场分布情况,并研究了红豆处于该种特定磁场环境中,从发芽到生长7天的植株生长情况,研究结果表明磁场场强处于1.5~2.5 Gs(约3~5倍地磁场强度)时,其磁场对红豆生长起到了促进的作用。     

Measurement of safety factor using Hall probes on CASTOR tokamak

Hall sensors offer an attractive true non-inductive method of magnetic field measurements for fusion devices. However, there is only limited experience in using of these sensors in such demanding environment (high heat loads, radiation, and electromagnetic noise). Recently, a combined magnetic probe was developed for CASTOR tokamak, which contains 3 Hall sensors and 3 coils arranged to measure all three components of magnetic field approximately in a single point of space. The probe is compatible with in-vessel use well in confinement region of CASTOR. It is fully controlled by multi-functional electronic system that drives the Hall probes, amplifies their output signals, performs the A/D conversion and stores the measured data on PC. The bandwidth of the system is up to 200 kHz. Design of the system and its implementation on CASTOR is reviewed. Results obtained using this diagnostic on CASTOR tokamak is presented. Radial profile of the poloidal magnetic field is used to deduce radial profile of safety factor.     

利用霍尔效应测磁场实验的数据处理

推导了亥姆霍兹线圈产生磁场的全空间分布的普遍公式,讨论了如何确定磁感应强度的方向。就实验内容进行了实例分析,利用Matlab软件进行了相关计算,提出了利用霍尔效应测磁场实验的数据处理方法。最后,详细讨论了亥姆霍兹线圈所在平面处磁场强度相关参数的分布曲线。