Compton散射下横等离激元与对等离子体作用特性

应用多光子非线性Compton散射模型、横等离激元色散方程和Karpman方法,研究了Compton散射对横等离激元与对等离子体作用特性的影响,提出了将入射超强激光和Compton散射作为横等离激元与对离子等离子体非线性作用新机制,给出了横等离激元非线性控制方程、等离激元数和能量公式。结果表明:与散射前相比,Compton散射使等离子体密度发生剧烈扰动,高频横等离激元与低密度扰动耦合非线性增强,导致横等离激元落入低密度区的几率增大。等离子体非线性频移和高密度区能量增加,低密度区能量减小,导致横等离激元电场包络迅速坍塌,等离激元数增加,场强度更强。     

合肥光源直流流强检测器系统的磁屏蔽

分析和测试了合肥光源杂散场对直流流强检测器系统的影响。给出了合肥光源ＤＣＣＴ系统的磁屏蔽的计算、设计和测量结果。屏蔽后,由杂散场引起的ＤＣＣＴ零漂由１ｍＡ降至１０μＡ以下。     

三腔渡越管振荡器高频结构的解析研究

 从圆柱坐标系下Borgnis位函数的齐次标量Helmholtz方程出发,引入慢波驻波概念及其场表达式,利用Borgnis位函数的边界条件及相邻子区公共界面上的场匹配条件,导出了三腔渡越管振荡器内角向均匀TM模的色散关系及场分布的解析表达式。运用该解析法求得三腔渡越管振荡器的谐振频率与实验中测得的微波频率一致,求得的场分布与数值法得到的场分布十分吻合。     

双反射膜双频He-Ne激光器双频特性及偏振特性的实验研究

本文对 5 MHz频差双反射膜双频 He- Ne激光器输出激光的双频特性及偏振特性进行了实验研究。研究结果表明 ,当磁场方向同反射膜的一个本征模方向基本重合时 ,有双频出现 ;当磁场方向同反射膜的一个本征模方向夹角在 45°左右时 ,无双频出现。输出激光的偏振方向由反射膜的本征模确定 ,其偏振非正交程度为 tgρ≤ 0 .0 0 87,椭圆化程度tgβ随激光管与磁场的相对角位置变化而发生变化。在合适的位置 ,tgβ可以小至 2 / 70 0。该种外差光源具有较好的偏振特性。     

一类二维流场模型的周期解与浑沌解的共存性*

本文研究Kelvin-Stuart猫眼流在周期扰动下的动力学行为,运用Melnikov方法确定出振动型周期轨产生偶数阶次谐分枝、旋转型周期轨产生任意阶次谐分枝的条件,并进一步发现周期解与浑沌解共存的复杂现象.     

Deformation of dispersely failing unidirectional composites

An anisotropic medium is considered in which, upon loading, scattered microdamages accumulate giving rise to nonlinear and residual strains. The damage at a point of the medium is characterized by a scalar function on a unit sphere, referred to as the damage function. This function is approximated by a fourth-rank tensor used for specifying the relation between the increments of strains and stresses. The calculation dependences are presented in detail for a unidirectional composite, which is taken to be a homogeneous transversely isotropic medium. Determination of the unknown constants is illustrated by the example of an actual fiberglass plastic. Institute of Polymer Mechanics, University of Latvia, Riga, LV-1006, Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 5, pp. 561–574, September–October, 1999.     

Bending features of a sandwich panel with asymmetric structure under local loads

The bending characteristics of a composite panel with asymmetric layered structure under local surface loads are obtained. A refined version of the applied theory is developed using the analytical solution of the bending problem of a sandwich plate with arbitrary asymmetric structure under a point load. Local effects are investigated within the limits of a discrete model allowing for the specific character of elastic properties of a soft filler. The advantages of the solution are expressions of bending characteristics — layer curvatures, displacements, and stresses — in a closed form. It is shown that these characteristics can vary several times depending on the asymmetry parameters of the structure. Degeneration peculiarities of the solution, stemming from the slipping of layers or, otherwise, their rigid linking by the Kirchoff—Love hypothesis, as well as from account of the transverse shear and compression of the normal, are examined in line with the degeneration of geometric and physical parameters of the discrete model adopted. The results obtained are illustrated by curves and surfaces for the characteristics studied.Submitted for the 11th International Conference on the Mechanics of Composite Materials (Riga, June 11–15, 2000).Institute of Polymer Mechanics, Latvian University, Riga, LV-1006 Latvia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 6, pp. 717–742, November–December, 1999.     

Derivation of the general form of elasticity tensor of the transverse isotropic material by tensor derivate

SymbolsU--FunchonofstrainenergyQ--OrthonormaltensorE--StraintensorEar--ComponentsofthestraintensorE,i,j=l,2,3n--VectorofthesymmetricaamsofthetransverseisotropicmaterialU*,E.,n*--FormsofU,EandninanothercoordinatesystemJf--MaininvariantsofstraintensorE,i=l,2,3Jf'n--InvariantsofstraintensorEconnectingwithvectorn,i=4,5Ji--TheabbreviatedformsofJf,Jf,Jf,Jf,",Jf,",i=l,2,3,4,5fi--ConstantsindependentonE,n,i=l,2,3,4,5el,e"--Thecovariantandcontravariantofthonormalbasisoftheusedcoordinatesyste…     

Near-field effect in optics of small objects composed of dipole atoms

A self-consistent problem of interaction of two dipole atoms separated by an unrestricted distance with the field of a quasi-resonance light wave was solved on the assumption that the investigated atoms are Lorentz linear oscillators and the polarizing fields inside the system consist of the Coulomb and the retarded parts. The solution obtained was investigated for the case where the atoms have the same polarizability and the distance between them is much smaller than the length of the external light wave. Formulas for the electric fields inside a small object and outside it have been obtained. It is shown that inside a small two-atom object there can take place longitudinal and transverse optical vibrations accompanied by corresponding dispersion effects depending on the interatomic distance and the angle between the axis of the system and the direction of propagation of the external light wave. The field outside the small object in the wave zone is linearly polarized when the external wave has linear polarization. However, the direction of polarization of the corresponding waves is largely determined by their frequency. It is also shown that the amplitude of the field outside the small object in the wave zone depends greatly on the frequency of the external field and the interatomic distance. The effects observed are considered as a near-field effect in optics of small objects. This phenomena makes it possible to investigate the structure of small objects with the use of optical radiation. Ul'yanovsk Branch of the Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 48 Goncharov Str., Ul'yanovsk, 432700, Russia; e-mail: gadomsky@quant.univ.simbirsk.su. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 765–770, November–December, 1999.     

两束脉冲激光在级联的三能级系统中的传播

利用密度矩阵方程和麦克斯韦传播方程的耦合考虑激光脉冲的横向效应,在柱对称的条件下,研究了两束脉冲在级联系统中的共振传播,考察了脉冲在光学厚介质中的时空演化过程。数值计算中考虑了两个能级的自发辐射速度,给出了脉能量的空间演化及电熟粒子在空间的分布。