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 共查询到17条相似文献,搜索用时 46 毫秒
1.
崔元顺  周淮玲 《大学物理》2002,21(9):20-21,31
从介质的物态方程出发,研究旋波介质的色散性质,给出了波数随旋波参量和频率变化的关系。  相似文献   

2.
电磁波在旋波介质中的传播特性研究   总被引:3,自引:0,他引:3  
介绍了旋波介质的结构特征,讨论了旋波材料的电磁性质和物质方程,结合麦克斯韦方程和边界条件。给出了电磁波入射介质的反射系数和透射系数。,  相似文献   

3.
崔元顺 《大学物理》2004,23(10):25-27,31
运用并矢法求解广义Helmholtz方程,结合Fourier变换、留数定理等数学处理,给出方程的并矢Green函数解析表达式;并进一步就旋波介质给出其中色散关系的另外一种求解方法.  相似文献   

4.
崔元顺 《大学物理》2004,23(11):22-24,27
结合运动介质本构关系,运用并矢代数方法,求解运动介质中电磁场的色散关系.结果表明,波数k与波频ω之间仍然保持线性关系,其比例系数决定于波传播方向k与介质运动方向v之间的夹角θ、参考系之间的相对运动速度口以及静止介质折射率n’的大小.  相似文献   

5.
在旋波介质研究过程中,人们提出了多种形式的物质方程.由于表达形式和使用符号的不同,很容易造成误解和混淆.本文对常用的4种物质方程形式进行了推导和整理,给出了它们之间的对应关系.  相似文献   

6.
高频电磁波(如X射线、Y射线)在医疗上的诊断、工业上的金属探伤以及工程勘察等方面得到了广泛的应用.为什么高频电磁波能隔着皮肉去透视骨骼、内脏器官,探测出金属内部结构的缺陷呢?通过本文介质对高频电磁波的色散规律的讨论,就能回答这些问题.  相似文献   

7.
基于运动方程和广义麦克斯韦本构,推导了一维黏弹性局域共振型和布拉格散射型声子晶体的色散与耗散关系。结果表明:对于时间谐波传播问题,这两种声子晶体的色散关系中均不存在禁带,波的衰减完全依赖于黏性耗散和周期性调制,且周期性调制会增强这种耗散作用;相反,对于自由波传播问题,两种声子晶体的色散关系中均存在禁带,但在禁带之外,波的衰减仍需借助于黏性耗散和周期性调制。研究结果对于由高分子材料构成的层状复合材料中的应力波传播研究具有一定的意义。  相似文献   

8.
根据经典力学、电磁学知识和经典色散理论导出了介质对高频电磁波的色散规律;由此色散规律可以清楚看出几乎所有介质对于高频电磁波来说都成为透明介质;并以金属铜为例进行了验证.据此人们可以容易地理解高频电磁波的某些应用.  相似文献   

9.
采用等离子体流体理论,从线性扰动方程出发,研究了电子束电流大小对介质切伦科夫脉塞中束波相互作用色散关系的影响,得到了当等离子体返回电流能有效中和与不能有效中和电子束电流两种情形下色散关系和波的增长率,并讨论了电子束电流对束波相互作用色散关系和波增长率的影响。研究表明,等离子体返回电流能有效中和与不能有效中和电子束电流两种情况下有着不同的色散关系和波的增长率。在波导参数和背景等离子体参数固定的情况下,电子束电流并不是越大越好,电子束电流过大不利于提高器件效率,它们之间存在最佳匹配关系。  相似文献   

10.
采用等离子体流体理论,从线性扰动方程出发,研究了电子束电流大小对介质切伦科夫脉塞中束波相互作用色散关系的影响,得到了当等离子体返回电流能有效中和与不能有效中和电子束电流两种情形下色散关系和波的增长率,并讨论了电子束电流对束波相互作用色散关系和波增长率的影响。研究表明,等离子体返回电流能有效中和与不能有效中和电子束电流两种情况下有着不同的色散关系和波的增长率。在波导参数和背景等离子体参数固定的情况下,电子束电流并不是越大越好,电子束电流过大不利于提高器件效率,它们之间存在最佳匹配关系。  相似文献   

11.
That millimeter wave propagation through a chiral medium of human trunk has been discussed by obtaining the electromagnetic filed, absorbent power, specific absorption rate, temperature field and their distribution in a human trunk model with plane strati calate homogeneous tissues under a normal incidence plane wave. The chiral medium is described electromagnetically by the constitutive relationsD=E+B andB=H+E. The constants, and ate real and have values that are fixed by the size, the shape, and the spatial distribution of the elements that collectively compose the medium. Also, the principle of thermal therapeutics for millimeter wave is discussed preliminaryly.  相似文献   

12.
The dynamics of frequency-modulated pulses in an isotropic nonreciprocal chiral medium is studied. It is shown that the discrepancy between the group velocities and carrier frequencies of the circular components of the pulse causes it to split up both along the fiber and in the spectral domain. The strong dependence of the material parameters on the pulse frequency may lead to the asymmetric dynamics of the electric and magnetic fields of the pulse in different frequency intervals. For both components of the wave field, envelopes moving with a supraluminal speed may arise.  相似文献   

13.
Field analysis of a general chiral planar waveguide   总被引:1,自引:0,他引:1  
The propagation characteristics of general chiral planar waveguides are presented. This is the first time the eigen equation is given in a simple formulation. The results indicate that there are two types of field distribution which is related to the working wavelength and chiral admittance. When the chiral admittance is larger than a certain value, the fields of one kind of circularly polarized wave in the core become exponentially damping in the transverse direction. This work was supported by the “Foundations for the Ph.D Programs of China”  相似文献   

14.
In this work, the concept of left-handed chiral metamaterials is analyzed by emphasizing their optical ability on the rotation of the plane of polarization of a wave. The possibilities of a negative phase velocity, negative and positive propagation constants, and basic electromagnetic properties of this novel medium are also presented. After the characterization of left-handed chiral metamaterial, we provide a reflection and transmission study for two planar boundaries of nonchiral-left-handed chiral metamaterial for normal angles of incidence. Some numerical results are also provided to validate the formulation found in the analysis and to show the role of the chirality in the propagation constants, phase velocities, reflection and transmission.   相似文献   

15.
We investigated the spatiotemporal modulation instability (MI) in a medium with a non-instantaneous Kerr response in which the nonlinear contribution to the refractive index is governed by a relaxing Debye type equation. The expression for the MI gain spectrum in non-instantaneous Kerr medium is obtained, which clearly reveals the influence of the finite time of the nonlinear response (relaxation effect) on the spatiotemporal MI. It is shown that, due to the relaxation effect, the spatiotemporal MI can appear for the case of anomalous dispersion and defocusing nonlinearity, while it cannot appear in instantaneous Kerr medium for the same case, and a new MI gain spectrum appears, adding to the conventional MI gain spectrum similar to that in an instantaneous Ker medium. In addition, the bandwidth of MI gain spectrum is extended and the maximum MI gain is reduced with increasing of the relaxation time. Interestingly, spatiotemporal MI can appear for any spatial frequencies in non-instantaneous Kerr medium for any combination of dispersion and nonlinearity. We have performed an experiment of MI in carbon disulfide (CS2), a typical non-instantaneous Kerr medium, which shows quantitative agreement with the theoretical analyses.  相似文献   

16.
王华英  赵中华  刘琳 《大学物理》2004,23(6):8-10,28
讨论了磁各向异性理想介质中平面电磁波的一般特性,继而推证了这种介质中平面波的对偶关系,导出了磁晶体中的“菲涅耳方程”,并利用此方程分析了这种理想介质中的平面波的结构、传播及其偏振特性.  相似文献   

17.
The behavior of a quasi-monochromatic nonlinear wave near a caustic is considered. Nonlinear ordinary differential equations for a dispersive dissipative medium with a cubic or quadratic nonlinearity are derived. For the latter medium, nonstationary equations describing it near the caustic are presented with allowance for the dissipative dispersive terms. These equations yield ordinary ones for quasi-monochromatic waves. The amplitude of the second harmonic is expressed in terms of the squared amplitude of the first harmonic. The amplitude of the second harmonic, as well as the solution as a whole, increases near the caustic.  相似文献   

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