也论电磁波的预言及其发现过程

文章根据麦克斯韦的著作和赫兹的《综合文集》、《电波》和《回忆、书信和日记》以及相关文献，对麦克斯韦预言电磁波的问题和赫兹实验发现电磁波的过程进行了仔细考察，指出麦克斯韦没有明确预言电磁波的存在，麦克斯韦的理论不是赫兹电磁学实验研究的直接指导思想．文章认为亥姆霍兹为普鲁士科学院所提出的1879年悬赏课题对赫兹发现电磁波起到了直接的引导作用，而电磁波的发现则主要归因于赫兹精湛的实验技能和敏锐的观察力．     

太赫兹波在非磁化等离子体中的传输特性研究

本文对太赫兹波在非磁化等离子体中的传输特性进行了理论和实验研究,得到了非磁化等离子体中太赫兹波传输特性随太赫兹波频率、等离子体密度、碰撞频率和厚度的变化规律．发现了一些新的现象：随着太赫兹波频率增加,反射率曲线出现周期性振荡,振荡周期为0．03THz．随着太赫兹波频率增加,振荡幅度增加：随着等离子体密度增加,振荡幅度减小;随着等离子体碰撞频率增加,振荡幅度增加．反射率曲线出现振荡的原因是电磁波在z=0和z=-d界面处的多次反射所致．以激波管为实验平台进行了0．22THz太赫兹波在等离子体中传输特性的实验研究,实验结果和理论结果符合较好．理论和实验结果均表明,采用太赫兹来实现地面与飞行器之间的通信互联是解决黑障问题的可选途径之一．     

赫兹和电磁波的发现

一百年前1),德国物理学家赫兹在实验上发现了电磁波.这是物理学史上的一件大事,也是人类文化史上的一件大事,因为它确定了麦克斯韦电磁理论的正确性,开辟了物理学的新领域,也为电磁波的应用打开了大门,导至了无线电通信和电视的出现,极大地丰富了人类的生活.为了纪念这一重大发现的一百周年,我们在这里对赫兹生平和他发现电磁波的经过,作一简单介绍. 一、赫兹生平简介 赫兹(Hertz,Heinrich Rudolf)于 1857年2月22日生于德国汉堡的一个比较富裕和有文化的家庭里.他六岁上小学,成绩优秀,名列第一.他爱好做实验,十二岁时家里给了他一些木工工…     

太赫兹量子级联激光器研究进展

太赫兹技术涉及电磁学、光电子学、半导体物理学、材料科学以及微加工技术等多个学科，它在信息科学、生物学、医学、天文学、环境科学等领域有重要的应用价值．太赫兹辐射源是太赫兹频段应用的关键器件．本文简要介绍了太赫兹电磁波的研究背景、重要特点以及潜在应用，重点讨论了太赫兹半导体量子级联激光器的工作原理和研究进展等．     

亥姆霍兹对电动力学发展的重要影响

文章结合19世纪70年代电动力学发展的特殊历史背景,从理论和实验两个角度讨论了亥姆兹在电动力学方面的重要工作,指出他要促使我们接受麦克斯韦理论以及引导赫兹成功地发现电磁波方面都发挥了重要作用,对赫兹和洛伦兹的电动力学理论研究产生了重要而又深远的影响,从而极大促进了经典电动力学的发展。     

掺钼ZnO透明导电薄膜的太赫兹电磁波传输性质

采用直流磁控反应溅射方法,通过调节氧分压在玻璃基底上制备了不同载流子浓度的掺Mo的ZnO（ZMO）透明导电薄膜.应用太赫兹电磁波时域光谱技术研究了ZMO导电膜的太赫兹电磁波透射性质及介电响应,得到了与频率相关的电导率、能量吸收和薄膜折射率,实验结果与经典Drude模型相符很好.ZMO导电膜的太赫兹电磁波脉冲透射性质表明,通过调节ZMO薄膜的载流子浓度,该导电膜可作为应用于衬底和光学器件等太赫兹电磁波频率范围的宽带抗反射涂层. 关键词： 太赫兹电磁波光谱 薄膜电导率 宽带抗反射 透明导电薄膜     

微波技术的发展与应用

 微波是指波长在1mm～1000mm、频率在300MHz～300GHz范围之间的电磁波,因为它的波长与长波、中波与短波相比来说,要“微小”得多,所以它也就得名为“微波“了。微波有着不同于其他波段的重要特点,它自被人类发现以来,就不断地得到发展和应用。19世纪末,人们已经知道了超高频的许多特性,赫兹用火花振荡器得到了微波信号,并对其进行了研究。但赫兹本人并没有想到将这种电磁波用于通信,他的实验仅证实了麦克斯韦的一个预言--电磁波的存在。20世纪初期对微波技术的研究又有了一定的进展,1936年4月美国科学家SouthWorth用直径为12.5cm青铜管将9cm的电磁波传输了260m远,波导传输实验     

太赫兹与远红外频段下铝质目标电磁特性与计算

在太赫兹与远红外频段,铝处于由导体到介质的过渡,研究该频段铝质目标与电磁波的相互作用机理对于实现太赫兹频段目标精确电磁散射计算具有重要意义.基于实验测量数据,设计有效误差准则模型拟合得到了太赫兹与远红外频段铝的介电系数模型;基于拟合模型通过推导过渡阶段不同损耗机理下铝中传播电磁波的空间相位系数与铝的波阻抗等参数,分析了太赫兹与远红外频段电磁波在铝中的透射与反射特性,给出了铝的反射率关于频率的变化曲线.结果表明铝中电磁波传播参数从微波向太赫兹频段过渡时具有很好的连续性与一致性;基于阻抗边界条件的雷达散射截面计算结果表明太赫兹频段光滑铝质目标可视做理想导体进行计算,太赫兹雷达散射截面测量中可利用光滑铝板或铝球做为定标体.     

超低温高电场下GaAs的电子太赫兹功耗谱的研究

利用自由空间太赫兹电光取样方法,测量了在高电场下,GaAs中受飞秒激光脉冲激发的电子所辐射出的太赫兹电磁波,发现从样品中辐射出的和电子加速度成正比的太赫兹电磁波电场强度E_THz（t）,表现出双极特性.通过分析GaAs中辐射出的太赫兹电磁波的傅里叶变换谱,首次实验上得到在阶跃电场下的GaAs的电子太赫兹功耗谱.研究发现,当电场小于50 kV/cm时,由电子谷间散射引起的负功耗（即增益）的截止频率ν_c,随着电场的增大而增大;当电场大于50 kV/cm时,负功耗的截止频率ν_c开始在750 GHz（10 K）附近饱和. 关键词： 太赫兹 非平衡载流子 功耗谱 谷间散射     

略论电磁波的发现

一些技术史文献试图从技术的角度来阐述电磁波发现的过程,但都无法单一地从技术方面说清它的理论渊源及与理论预言的实验证明的过程.本文试图从电磁学的历史背景、麦克斯韦的理论预言和赫兹的实验证明等方面,来初步讨论发现电磁波的全过程. 一、安培超距论电动力学和 法拉第电磁场论的诞生 1820年4月,丹麦物理学家奥斯特发现了电流的磁效应,它标志着电磁学的开始. 自从库仑时代以来,法国物理学家们一反其祖辈笛卡尔的涡旋运动的思想,跟随拉普拉斯的物理学简略纲领,将一切物理现象都简化为粒子间的吸引或排斥的力学现象.“电学中的牛顿”──…     

On the validity of Hertz contact law for granular material acoustics

We discuss the acoustical behavior of a 1D model of granular medium, which is a chain of identical spherical beads. In this geometry, we are able to test quantitatively alternative models to the Hertz theory of contact between elastic solids. We compare the predictions of the different models to experimental results that concern linear sound wave propagation in the chain submitted to a static force, and nonlinear solitary wave propagation in an unconstrained chain. We use elastic, elastic-plastic and brittle materials, the beads roughness extends on one order of magnitude, and we also use oxidized metallic beads. We demonstrate experimentally that at low static forces, for all types of beads, the linear acoustic waves propagate in the system as predicted by Hertz's theory. At larger forces, after onset of permanent plastic deformation at the contacts, the brass beads exhibit non Hertzian behavior, and hysteresis. Except in the case of brass beads, the nonlinear waves follow the predictions of Hertz theory. Revised: 28 May 1998 / Accepted: 27 July 1998     

From Propagation to Structure: The Experimental Technique of Bombardment as a Contributing Factor to the Emerging Quantum Physics

I observe that quantum physics emerged at the turn of the last century when physics had shifted its concern from propagation phenomena to questions of structure. This transition materialized with the development of a new experimental technique, the bombardment method. The transition is well exemplified by the move from the experimental studies of Heinrich Hertz to those of Ernest Rutherford, and from those of Heinrich Hertz and Philipp Lenard to those of James Franck and Gustav Hertz. I trace the history of Rutherford's experimental bombardment method as it emerged from nineteenth-century propagation studies. I then demonstrate the use of the bombardment method in another experimental context, namely, in the celebrated experiment of Franck and Hertz. I locate the root of this experiment in Lenard's experimental studies and analyze Franck and Hertz's flawed interpretation of it. I conclude by underlining the crucial role that Bohr's quantum theory of the atom played in helping to establish these bombardment experiments as milestones of modern physics.     

Interaction of intense laser radiation with weak electromagnetic waves in an evacuated section of a ring laser

A laboratory experiment for the study of nonlinear interaction of electromagnetic waves in vacuum is proposed. The basic idea of the experiment is as follows. If one separates a certain region of the circuit in a ring laser from the remaining part with gas-impenetrable partitions, evacuates it, and forms external electromagnetic fields there, the oscillation frequencies and the polarization states of the electromagnetic waves traveling in this ring laser in counter directions are different. A calculation is made for the oscillation frequencies of electromagnetic waves traveling in a ring laser in opposite directions in the case when they interact in an evacuated section of the ring laser circuit with intense laser radiation. It is shown that the effect can be observed in experiments using presently available pulsed lasers of ultrahigh power.     

声诱导电磁场的赫兹矢量表示与多极声电测井模拟

在假设声场不受电磁场影响的前提下，将Pride声电耦合方程组化为具有电流源的麦克斯韦方程组.与空间位置固定的电流源产生的电磁场不同，孔隙地层中声波诱导的电磁场是由空间波动的电流源产生的.通过引入赫兹矢量，将求解麦克斯韦方程组问题转化为求解关于赫兹矢量的非齐次矢量赫姆霍兹方程组.通过求解该方程组，得出电磁场表达式.利用此方法，针对声电效应测井，分别计算了由单极声源、偶极声源、四极声源激发的井内声场及其诱导电磁场的全波波形. 关键词： 孔隙介质 诱导电磁场 测井 多极声源     

Information (no-energy) waves described by global potentials

The case where the magnetic flux inside an electronic loop varies with time is considered for an experiment in which the Aharonov-Bohm effect is observed. The electromagnetic field and potentials of a solenoid with an alternating current are studied. It is shown that the vector potential outside the solenoid contains a term corresponding to a zero electromagnetic field at the same point of space. This part of the potential (global potential) describes standing waves whose properties differ from those of ordinary electromagnetic waves and which can be conventionally called information potential waves. A method of detecting information waves is proposed involving an effect similar to the Aharonov-Bohm effect (quasi-Aharonov-Bohm effect). Unlike ordinary electromagnetic waves, these information waves are not involved in any energy interactions but they can carry information.     

Politics,Morality, Innovation,and Misrepresentation in Physical Science and Technology

The pressures of politics, the desire to be first in innovation, moral convictions, and the potential dangers of error are all factors that have long been at work in the history of science and technology. Every so often, the need to reach a result may require leaving out a few steps here and there. Historians think and argue best through stories, so what follows are several tales, each of which exemplifies one or more of these aspects, though some reach back nearly two hundred years. The first concerns the depletion of the ozone layer; the second involves the discovery of electric waves by Heinrich Hertz in 1888; the third concerns the controlled production of electromagnetic radiation by Guglielmo Marconi and John Ambrose Fleming in the early 1900s; the fourth portrays the circumstances surrounding Joseph von Fraunhofer’s discovery and use of the spectral lines in the 1810s; our final case involves a bitter controversy between the physicist Hermann von Helmholtz and the astronomer Friedrich Zöllner in the 1890s.     

赫兹对阴极射线的实验研究及其重要影响

根据赫兹的日记、书信、文集及相关文献,对赫兹所进行的阴极射线的实验研究工作进行了仔细考察,指出他对阴极射线的一系列实验研究为揭示阴极射线的全部特性奠定了重要基础,对勒纳德和汤姆孙在这一领域的研究产生了直接影响．     

High-frequency emissions during the propagation of an electron beamin high-density plasma

A relativistic annular electron beam passing through a high-density plasma excites Langmuir waves via Cerenkov interaction. The Langmuir waves are backscattered off ions via nonlinear ion Landau damping. At moderately high amplitudes these waves are parametrically up-converted by the beam into high-frequency electromagnetic radiation, as observed in some recent experiments. A nonlocal theory of this process is developed in a cylindrical geometry. It is seen that the growth rate of the Langmuir wave scales as one-third the power of beam density. The growth rate of parametric instability scales as one-fourth the power of beam density and the square root of beam thickness     

Advances in gravitational radiation detection

New experiments are reported which improve our estimates of the bandwidth and energy flux of the observed radiation. These include search for coincident, sudden increases in power of newly instrumented detectors at 1661 Hertz and 1581 Hertz, at opposite ends of a 1000 kilometer baseline, and search for coincidences between outputs of detectors at 1661 Hertz and 5000 Hertz. Coincidences are observed for the detectors separated by 80 Hertz, implying a radiation bandwidth exceeding 80 Hertz.The new instrumentation is a modification of the earlier technique for bonding ferroelectric crystals to aluminium cylinders. Three detectors are fully operational with sensitivity one order better than earlier ones.Progress has been made in data retrieval employing a computer and magnetic tape. Earlier results on the coincidence rates and time delay experiments have been confirmed.A 1661 Hertz detector has been developed for operation at liquid helium temperatures. It is now undergoing tests at the Argonne National Laboratory.An experiment has been approved by NASA to employ the moon as a gravitational radiation detector. Equipment has been designed by Bendix and the University of Maryland for emplacement by the Apollo 17 astronauts.Supported in part by the U.S. National Science Foundation.Presented at the International Conference on Gravitation and Relativity, Copenhagen, 5–10 July, 1971.     

Ether drift experiments and electromagnetic momentum

Propagation of Aharonov-Bohm matter waves and light waves in moving media is characterized by the interaction electromagnetic momentum. Thus, recent models of light propagation in moving rarefied media justify and call for an optical experiment of the Mascart-Jamin type, capable of testing the modern interpretations of ether drift experiments.