Upgrading Radio-Frequency Electromagnetic Field Standards. Part 1

Stages are considered in incorporating the radio-frequency range in setting up standards for electromagnetic field parameters. The problems involved are discussed, together with methods and results from resolving them. The history of electromagnetic field standards is closely related to researches in two metrological centers: VNIIFTRI and NIST.     

The Beginning of the Metrology of Radio-Frequency Electromagnetic Fields and the First Standards of Electric Field Strength

The historical aspect of the origin and development of the metrology of radio-frequency electromagnetic fields is considered, beginning with Hertz's experiments. The first electric field strength standards in the 30–300 MHz frequency band are described. The results obtained are analyzed and estimated from the modern point of view.     

List of calibration and measurement capabilities of VINIIFTRI in the domain of measurements of electromagnetic fields

The role of the measurement standards of a radio-frequency electromagnetic field in an international system of calibration of measuring instruments is considered. The calibration and measurement capabilities of VNllFTRI in this domain are listed.Translated from Izmeritelnaya Tekhnika, No. 1, pp. 31–35, January, 2005.     

The present state and current problems of ensuring uniformity of measurements of the parameters of electromagnetic pulses

Information on how to construct and improve the State Special Standard of the units of pulsed electric and magnetic field strengths are presented. The need and possibility of extending the time range of the standard in order to ensure uniformity of measurements of the parameters of very short pulses of electromagnetic fields having a pulse length of down to 10^-10 sec are considered.Translated from Izmeritelnaya Tekhnika, No. 10, pp. 33–35, October, 2004.     

A reference model for a flowmeter magnetic field for a computing experiment

A reference model is considered for a magnetic field intended for checking programs and algorithms defining the electromagnetic field in an electromagnetic flowmeter measurement channel. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 39–41, April, 2007.     

Three-Dimensional Analytical Modeling of Axial-Flux Permanent Magnet Drivers

In this paper, the axial-flux permanent magnet driver is modeled and analyzed in a simple and novel way under three-dimensional cylindrical coordinates. The inherent three-dimensional characteristics of the device are comprehensively considered, and the governing equations are solved by simplifying the boundary conditions. The axial magnetization of the sector-shaped permanent magnets is accurately described in an algebraic form by the parameters, which makes the physical meaning more explicit than the purely mathematical expression in general series forms. The parameters of the Bessel function are determined simply and the magnetic field distribution of permanent magnets and the air-gap is solved. Furthermore, the field solutions are completely analytical, which provides convenience and satisfactory accuracy for modeling a series of electromagnetic performance parameters, such as the axial electromagnetic force density, axial electromagnetic force, and electromagnetic torque. The correctness and accuracy of the analytical models are fully verified by three-dimensional finite element simulations and a 15 kW prototype and the results of calculations, simulations, and experiments under three methods are highly consistent. The influence of several design parameters on magnetic field distribution and performance is studied and discussed. The results indicate that the modeling method proposed in this paper can calculate the magnetic field distribution and performance accurately and rapidly, which affords an important reference for the design and optimization of axial-flux permanent magnet drivers.     

A mathematical model of the identification of the magnetic field of a flowmeter

The construction of a mathematical model of the magnetic field in the measurement channel of an electromagnetic flowmeter by an identification method is considered. __________ Translated from Izmeritel’naya Tekhnika, No. 10, pp. 55–58, October, 2006.     

空心管坯电磁离心过程的数值模拟

用有限元法模拟了铸造合金的流动和热量传输过程中瞬态速度场和温度场的分布,研究了电磁场强度和离心机转速对电磁铸造空心管坯的影响.结果表明,电磁搅拌引起的熔体相对运动是凝固过程中晶粒细化的主要原因.最优的电磁搅拌条件:转速1200 r/min,磁场强度为0.08 T,磁场持续加载25 s.在一定的转速和磁场强度条件下电磁离心铸造的温度场和凝固时的温度梯度对凝固组织有重要的的影响.合金液的外层,温度梯度达到最大值,铸件的温度下降得快,容易形成细小的等轴晶.     

Metrological Provision for Measuring Electromagnetic Properties of Radio Engineering Materials at HF and UHF

The system of metrological provisions for measuring electromagnetic properties of materials at HF and UHF within Russia, and particularly within SNIIM, is considered. The main technical characteristics of domestic standards for measuring the electromagnetic properties of materials are provided and ways for further improvement of metrological provisions for these forms of measurement at the national metrological centers in Russia are discussed.     

振动驱动的电磁－永磁复合驱动建模

对一种新的电磁-永磁复合激励永磁体偏转驱动的机理进行振动应用理论分析和实验验证研究。对于这种电磁－永磁复合激励方式,提出一种基于面磁荷计算电磁扭矩的数值方法,建立电磁扭矩随电流和永磁体偏摆角度变化的数学模型,并将理论建模进行对比试验研究,验证所提出理论分析方法的正确性和基于永磁体偏摆驱动在振动驱动领域应用的可行性。     

A new features on S-waves propagation in a nonhomogeneous anisotropic incompressible medium under influence of gravity field and initial stress with and without electromagnetic field and rotation

The present article is concerned with the investigation of the propagation of shear waves in a nonhomogeneous anisotropic incompressible medium under the effect of the electromagnetic field, gravity field, rotation, and initial stress taking into account a comparison between presence and absence of magnetic field, initial stress, and rotation. Analytical analysis reveals that the velocity of propagation of the shear waves depends upon the direction of propagation, the anisotropy, magnetic field, rotation, gravity field, nonhomogeneity of the medium, and the initial stress. The frequency equation that determines the velocity of the shear waves has been obtained. Some special cases are also deduced from the present investigation. In fact, these equations are an agreement with the corresponding classical results when the medium is isotropic. Numerical results have been given and illustrated graphically in each case considered. The results indicate that the effects of gravity field, initial stress, magnetic field, electric field, anisotropy, and rotation are very pronounced. Also, the absence of initial stress, magnetic field, and rotation tends to increasing of the S-waves velocity compared with presence of them.     

On the propagation of waves in an electromagnetic elastic solid

The coupling of electromagnetic and elastic waves is considered from the standpoint of linear elasticity and a linearized electromagnetic theory. The problem of plane waves traveling through a uniform magnetostatic field is considered and couplings of the waves are studied. An investigation of the same problem for a uniform electrostatic field shows that the usual plane waves propagate without any change in their phase velocities but that the mechanical waves are accompanied by small fluctuating electromagnetic fields. The problem of the vibration of a free infinite elastic plate in a large magnetostatic field is examined under the assumption that the resulting electromagnetic fields are quasistationary. Frequency equations are obtained for both symmetric and antisymmetric vibrations and the damping caused by the field for both the first two symmetric and antisymmetric modes is obtained as a linear correction to the usual free plate frequencies.     

Microwave Standards and Measurements, A Progress Review 1960 to 1963

Rather than a comprehensive survey of the field, highlights of the progress in microwave standards and measurement methods are given. Power, attenuation, impedance or reflection coefficient, noise, phase shift, and field strength are covered. Microwave frequencies are assumed to start at 1 Gc and extend upwards, including coherent electromagnetic energy in the spectrum of visible light, approximately 400-800 Tc. A discussion of the intercomparisons of power standards of different nations is followed by a report on newly developed power measuring devices and techniques. Some methods of measuring the power of lasers are given. The present status of attenuation measurements and standards is indicated, giving ranges and accuracies of calibrations at the National Bureau of Standards, Boulder, Colo. New types of standards for millimeter and submillimeter waves and for attenuation of laser beams are mentioned. Impedance standards and measuring techniques are discussed, as well as 2-port measurements and the development of greatly improved coaxial connectors. The recent development of phase shift standards and measurement techniques in the United States is summarized. The essential lack of microwave field strength standards is noted and small progress is reported.     

磁控溅射中电磁场分布及带电粒子运动的模拟与计算

电磁场分布及其对各种带电粒子的约束情况对磁控溅射过程有着决定性的影响。本文首先利用物理场耦合分析软件Comsol 3．2a分析了直流磁控溅射电磁场的分布，并且计算分析了单个带电粒子的运动情况。在此基础上，计算分析了带电粒子束流在电磁场中的运动情况、空间分布，得到了磁控溅射电磁场区域分布、单个电子的运动轨迹及带电粒子在空间区域中位置分布。     

组合电磁场在材料凝固过程中的应用和发展

组合电磁场是指通过2个或者2个以上励磁线圈,产生2个或2个以上交互作用的电磁场,并将交互作用的电磁场作用于材料制备过程.组合电磁场在金属凝固过程中的应用可为开发新材料、优化材料制备工艺、提高金属材料制品的综合质量和解决金属材料在制备过程中的技术难题提供新的手段和方法.组合磁场在材料凝固过程中的应用必将成为材料研究领域的新方向.     

Effect of external magnetic fields on shaped-charge operation

This paper deals with electromagnetic actions that allow one to control the shaped-charge effect at different stages of shaped-charge operation. A decrease in penetration of the shaped-charge jet is attained by production of an axial magnetic field in the shaped-charge liner immediately before shot, and production of a magnetic field in the conducting target material that is transverse to the direction of jet propagation. The considerable decrease in the penetration capability of the charge observed in the experiments is attributed to a sharp amplification of the magnetic field in the jet formation region upon liner collapse. The effects accompanying the “field pumping” prevent the normal formation of a shaped-charge jet. A model of magnetic field generation in a conducting medium subjected to high-velocity deformation with particle elongation along the magnetic flux lines is considered. X-ray photographs of shaped-charge jets formed from a “magnetized liner” are given. Theoretical calculations have shown that deformation conditions that can provide for intense magnetic field generation also arise during high-velocity jet penetration into a conducting target across the flux lines of the initial magnetic field previously produced in the target.     

静磁场在材料生产过程中的应用研究评述

在材料电磁过程研究中，静磁场尤其是强磁场材料科学是当今世界的研究热点。本文从静磁场作用下生成的洛仑兹力和磁化力两个角度系统地归纳总结了静磁场技术在材料生产领域的应用原理和实践。对静磁场下的洛仑兹力，主要介绍了流体流动、波动和对流控制、电磁振动及电磁超声波等方面的研究现状；对强磁场下的磁化力，主要介绍了其在相变、结晶配向、磁悬浮、磁对流等方面的研究进展。最后对强磁场材料科学的研究趋势和发展前景做了展望。     

Effect of Low Frequency Electromagnetic Field on Macrosegregation of Horizontal Direct Chill Casting Aluminum Alloys

The horizontal direct chill (HDC) casting process is a well-established production route for aluminum alloy ingot but the ingot may suffer from macrosegregation sometimes. In order to control the defect, a low frequency electromagnetic field has been applied in HDC casting process and the relevant influence has been studied. The results show that application of low frequency electromagnetic field can reduce macrosegregation in HDC casting process; and two main parameters of electromagnetic field density and frequency, have great influences on the solution distribution along the diameter of ingot. Moreover, the mechanisms of reduction of macrosegregation by electromagnetic field have been discussed.     

热金属气压成型电磁感应加热有限元模拟

应用感应加热理论,利用麦克斯韦方程组和温度微分方程,建立了电磁场与温度场耦合的有限元数学模型,使用有限元分析软件ANSYS对热金属气压成型工艺中的电磁感应加热过程进行了模拟与分析。模拟结果表明:随着电磁感应线圈电流频率的提高,在相等的加热时间内,金属钢管的升温速度不断增加,且最终达到的温度也进一步升高。随着电磁感应线圈电流密度的增加,在相等的加热时间内、相同的电磁感应线圈电流频率下,金属钢管的升温速度不断增加,加热效率得到有效提高,且最终达到的温度也逐步升高。随着金属钢管与线圈的间隔增加,金属钢管内、外表面的温度均逐渐降低;外表面温度的降低趋势越来越平缓,而内表面温度的降低趋势则不断加剧。     

电磁场作用下半固态合金熔体流动行为对凝固组织的影响

电磁场技术在半固态合金加工中的应用促进了制备工艺的开发和创新,也为获得高质量的半固态合金制品提供了保障。电磁场引起的半固态合金熔体流动状态和性质对合金元素传输、晶粒长大、温度场分布、凝固组织等均有重要影响。主要综述了电磁场对半固态合金流动行为的影响、数值模拟技术在解析半固态合金流动行为中的应用等方面的研究进展,并结合笔者的研究经历介绍了电磁场搅拌技术在半固态合金浆料制备中的应用、熔体流动对半固态合金凝固组织的影响,以及在半固态合金熔体流动特性研究中的新发现。在这些研究工作的基础上,着重综述了应用商业软件和数学建模对半固态合金熔体中电磁场作用引起的流动行为进行模拟、仿真所做的工作和取得的成果。最后,对电磁场技术在半固态合金加工中的应用以及电磁场作用下半固态合金熔体流动特性对半固态合金凝固组织影响的研究进展进行了总结,并对其发展前景和主要发展方向进行了展望。