不同功率下无工质微波推力器的推力预估

基于经典电动力学理论,从麦克斯韦方程组和麦克斯韦张量出发,推导出无工质微波推力器的推力计算方程. 应用有限元分析软件,计算了特定谐振模式下的特定圆台谐振腔在不同功率条件下的电磁场分布;根据推导出的理论计算公式,计算了不同功率条件下推力器的总推力. 计算结果表明:推力与功率成正比,而且磁场力决定着总推力的大小;圆台谐振腔消耗20–200 W电磁波功率时所产生的推力在20–250 mN范围内. 关键词： 电磁波 麦克斯韦张量     

开尔文在电磁理论发展中的作用

 提到电磁理论,人们首先想到的是法拉第、麦克斯韦,而对开尔文在电磁理论发展中的作用则知之甚少,本文就介绍一下这方面的情况.     

肉类的微波与红外线保鲜实验

从电磁生物效应出发,分析了微波与红外线对细胞的作用,介绍了微波与红外线的保鲜技术. 通过微波与红外线照射猪肉片的实验,研究了2种电磁波对肉类保鲜的作用. 结果表明在一定的时间内二者均有一定的延缓肉类腐败提高新鲜度的作用.     

二级轻气炮弹丸速度过程测量实验技术

轻气炮弹丸在膛内的速度、加速度及弹底压力是轻气炮及发射系统设计的关键参数，实验测量这些参数对完善内弹道理论、研究新型轻气炮以及对常规武器进行校验等有着非常重要的指导意义。     

Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system

A microwave thruster system that can convert microwave power directly to thrust without a gas propellant is developed. In the system, a cylindrical tapered resonance cavity and a magnetron microwave source are used respectively as the thruster cavity and the energy source to generate the electromagnetic wave. The wave is radiated into and then reflected from the cavity to form a pure standing wave with non-uniform electromagnetic pressure distribution. Consequently, a net electromagnetic thrust exerted on the axis of the thruster cavity appears, which is demonstrated through theoretical calculation based on the electromagnetic theory. The net electromagnetic thrust is also experimentally measured in the range from 70 mN to 720 mN when the microwave output power is from 80 W to 2500 W.     

Micromorphic Electromagnetic Theory and Waves

This paper introduces a continuum microelectromagnetic theory (also called micromorphic electromagnetic theory), to discuss electromagnetic phenomena in bodies with microstructures. Balance laws of microelectromagnetic media of the first-grade are given. Constitutive equations are developed. The field equations are obtained . It has been shown that, this theory gives rise to several new vector and tensor waves. A theorem of conservation of energy (Poynting type) is proved. Dispersion relations are obtained for both vector and tensor waves. Relations of tensor waves to microscopic phenomena (such as spin waves) are discussed.     

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．     

Cross sections of multiparticle photonuclear reactions with <Superscript>203, 205</Superscript>Tl isotopes

An experiment on the irradiation of the natural mixture of ^203,205Tl isotopes by the bremsstrahlung beam of pulsed racetrack microtron RTM-70 (Skobeltsyn Institute of Nuclear Physics, Moscow State University) at an electron energy of 67.7 MeV was performed. The yields and integral cross sections of multiparticle photonuclear reactions with ^203,205Tl isotopes were measured.     

Analysis of Trapping Force and Torque for Fiber-optical Trap by the Finite-differential Time-domain (FDTD) Method

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A raman spectroscopic study of the interactions of 13 GHz microwave irradiation with dipalmitoylphosphatidylcholine dispersions

Summary In order to clarify the effect of 13 GHz microwave irradiation upon model membranes, vibrational Raman spectroscopy was performed for multilamellar dispersions of dipalmitoylphosphatidylcholine, before and after irradiation. Raman spectra of the phospholipid dispersions were recorded for the C−H ((2800⊢3100)cm⁻¹) and the C−C ((1050⊢1150)cm⁻¹) stretching modes, above the transition temperatureT _m of the phospholipid, before and after microwave irradiation. An intensity comparison between the irradiated and nonirradiated sample revealed an increase in the intensity ratioI ₂₉₃₀/I ₂₈₈₀ and a small perturbation in the C−C stretching region, induced by microwaves. It seems reasonable to assume that microwave irradiation brings about a change in lateral chain-chain interactions, which is possibly due to induced changes at bilayer curvature.     

运动介质的电磁性质方程

应用电磁场张量、电磁感应张量和它们的对偶张量讨论运动介质的电磁性质方程,指出D=εE和B=μH在运动介质中不成立,给出运动介质电磁性质方程的协变形式、向量形式.     

多普勒雷达测量电磁轨道炮内弹道速度

介绍了W波段多普勒雷达测量电磁轨道炮内弹道度速度的基本方法,并对口径30mm×25mm的串联增强型电磁轨道炮内弹道速度进行了实际测量。初步研究表明:雷达接收的信号易受到脉冲放电过程的干扰;雷达信号的信噪比取决于电枢与轨道电接触状态,在电源充电电压较低、接触面无电弧生成时测得了完整的内弹道速度,并与丝网靶和磁探针测量结果吻合;在较高充电电压条件下,由于电弧电接触产生的干扰,测速结果不够理想。