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《光学学报》2015,(5)
研究带电粒子对电磁波的散射,对认识电磁场规律及云层探测、雷电预警等具有重要意义;根据带电粒子的米氏散射理论,对散射系数进行简化,得到了带电粒子在瑞利散射条件下,散射系数与面电导率和电磁阻抗系数的关系;计算了瑞利散射条件下,不同面电导率的粒子的电磁波散射系数,在粒子尺度较小时,瑞利散射公式与米氏散射公式计算结果一致。粒子表面所带电荷改变了面电导率,当面电荷使面电导率达到毫西门子量级时,就会使散射系数有明显增加,随着面电导率的增加,散射系数会有较大变化;对尺度系数较小的粒子,散射系数较小,但带电后散射系数与中性时的散射系数之比较大,并随着电导率的增加趋于一个恒定值,大小与粒子的介电系数有关,对球形水滴这一恒定值约为24。 相似文献
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气溶胶激光散射信号的特征分析 总被引:1,自引:0,他引:1
本文应用Mie散射理论对微球体粒子光散射的性质进行了理论分析与数值计算,得出了散射光分布与微球体尺度参数、复折射率之间的关系。结果表明:不同尺度参数的粒子的散射光强的分布相差极大,随着尺度参数的增加散射光强越来越集中于前向;复折射率的变化对散射光强影响不大。并且在边界层大陆乡村型霾的气溶胶模型下对大气气溶胶的体角散射系数进行了分析与数值计算,得出:气溶胶粒子的散射光强主要分布在前向,并且随着散射角的增加有规律的减小。由此提出了利用气溶胶粒子体散射系数的性质,通过测量散射点前向散射光强和延迟时间来实现激光束的近轴定位的方法。 相似文献
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首先建立大尺度分层介质粗糙面散射的物理模型, 基于Stratton-Chu积分方程和Kirchhoff近似导出了粗糙面散射场的计算公式. 采用高斯随机粗糙面来模拟实际的分层介质粗糙面, 通过数值计算得到了正下视单站雷达接收到的后向散射回波. 理论推导了散射场强度与表面粗糙度之间的定量关系, 并从数值仿真的角度分析了表面和次表面的粗糙度对散射回波的影响, 给出了散射场随粗糙度变化的曲线. 最后考察了分层介质的电特性参数(介电常数和电导率)对分层粗糙面散射场的影响, 并对计算结果做出了分析. 相似文献
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研究了球形粒子在聚焦拉盖尔-高斯光束中的散射特性. 根据广义Mie理论, 推导出球形粒子在聚焦拉盖尔-高斯光束中散射系数的解析公式. 针对光束的电场分布及粒子散射强度进行了数值仿真, 讨论了散射强度随散射角、散射球粒子半径和拓扑荷的变化特性, 并通过散射系数解释了散射强度分布的振荡现象. 结果表明, 在聚焦拉盖尔-高斯光束照射下, 球形粒子的后向散射强度随着粒子半径的增大而逐渐增大; 后向散射强度开始增大时对应的粒子半径与拓扑荷有关. 通过与高斯光束的对比, 可以看出球形粒子在聚焦拉盖尔-高斯光束中散射特性的差异, 使其在粒径测量、光通信和大气后向散射探测等方面具有潜在应用价值. 相似文献
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基于离散偶极子近似法(DDA),对水雾包裹沙尘颗粒的核壳结构光学特性进行研究,计算了长短轴比例为2∶1的椭球形粒子的核壳结构内、外层厚度及散射角度变化对光散射特性的影响。结果表明,内核大小不变,外层厚度由1.2 μm增大到4.8 μm,核壳双层颗粒散射系数和消光系数由3.4和3.43降低到2.543和2.545,且散射相对强度也明显增大。外层厚度不变,内核厚度由0.6 μm增加到2.4 μm,散射系数和消光系数由3.105和3.111变化为2.76和2.9;可见外层厚度对核壳双层颗粒散射特性的影响更大,这是由于散射光主要与外层物质相互作用引起的。散射相对强度随波长的增加而降低,随核壳结构尺度的增加呈现递增的规律。该结果对大气中气溶胶和水雾共同作用时的散射特性,激光在其中的传输特性等研究有参考价值。 相似文献
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浓悬浮体中多次散射对声波能量传输的影响 总被引:1,自引:0,他引:1
本文应用类似于光学中的传输问题建立起声波传输方程,用以解决声波在浓悬浮体中传播时考虑了微粒间的多次散射后声波能量的透射和反射问题。该方法较目前声学中采用的处理方法简捷,所依据的物理图像清晰,适用于粒子线度与波长的比为任意值的情况。本文还以刚性球形悬浮粒子为例,计算了声波的透射和反射与程长的关系,得出在浓度不太大时(散射系数×程长<0.256),当ka<1时不考虑多次散射不会产生很大误差,ka=3时,由于多次散射影响,散射系数减小5%,ka=5时散射系数减小14%。浓度增大时散射系数逐渐减小。此外还讨论了微粒线度分布、声接收器后部悬浮体的散射等对声能传递的影响。 相似文献
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非球形粒子的散射特性分析 总被引:1,自引:0,他引:1
本文首先利用T矩阵方法计算了复折射率吸收指数和折射指数变化时的椭球粒子和Chebyshev粒子在不同等效尺度参数下的光散射特性,并与等效的球形粒子的光散射结果进行了比较;然后分析以上两种类型非球形粒子散射特性之间的关系.结果表明:椭球粒子和Chebyshev粒子的散射特性与等效球形粒子的散射特性存在着差别,粒子的形状越偏离球形,这种差别就越大;复折射率折射指数的变化对非球形散射效率因子的影响要比吸收指数的影响更大一些;当等效尺度参数相同时,椭球粒子与等效球形粒子的散射效率因子的差别要远远大于Chebyshev粒子与等效球形粒子散射效率因子之间的差别. 相似文献
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瑞利散射和米氏散射现象的实验演示 总被引:1,自引:0,他引:1
硫代硫酸钠与稀盐酸反应时,会在溶液中缓慢产生不溶于水的固态硫分子,其直径小于可见光的波长;随着反应的进行,多个硫分子聚结形成较大颗粒,其直径接近并逐渐大于可见光波长.在上述反应过程中,利用白光照射溶液,可以分别观察到瑞利散射和米氏散射现象,并在文中研究和分析瑞利散射时光的偏振特性. 相似文献
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I. Y. Park 《The European Physical Journal C - Particles and Fields》2009,62(4):783-791
We analyze one-loop scattering amplitudes of the massless states on a stack of D3-branes. We use the vertex operators that
have been obtained in the direct open string analysis developed in . The method does not have the obstacle of the D9 computation which is associated with the appearance of an ε-tensor. The divergence structure is not the same as the D9-brane case. What makes the analysis deviate from the D9-brane
case is that the momenta of the states have non-zero components only along the brane directions. We ponder on the possibility
that the one-loop divergence may be canceled by adding additional vertex operators at the tree level. We anticipate that they
will be “exponentiated” to the free string action, with the resulting action to constitute a non-linear sigma model of the
D-brane/AdS geometry. 相似文献
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J. Dorenbosch F. Udo J. V. Allaby U. Amaldi G. Barbiellini M. Baubillier F. Bergsma A. Capone W. Flegel F. Grancagnolo M. Jonker L. Lanceri M. Metcalf C. Nieuwenhuis J. Panman R. Plunkett C. Santoni K. Winter I. Abt F. W. Büsser H. Daumann P. D. Gall T. Hebbeker F. Niebergall P. Stähelin P. Gorbunov E. Grigoriev V. Kaftanov V. Khovansky A. Rosanov A. Baroncelli L. Barone B. Borgia C. Bosio M. Diemoz U. Dore F. Ferroni E. Longo L. Luminari P. Monacelli S. Morganti F. de Natoristefani L. Tortora V. Valente 《Zeitschrift fur Physik C Particles and Fields》1991,51(1):142-142
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In recent experiments, very low amplitudes of light scattering were reported for a tightly focused laser beam on a glass microcapillary. This result may be of great importance for single molecule detection in liquids. In the present paper, a theoretical study of the problem of light scattering of a focused laser beam on a cylindrical glass capillary is given. The numerical calculations are based on an exact electrodynamic treatment of the whole problem, including vector effects of the electromagnetic field of the laser beam. It is shown that under favorite conditions (inner and outer radius of the capillary, perfect adjustment of the laser beam) the intensity of the back-scattered light may be extremely low. 相似文献
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I. Úlehla 《Czechoslovak Journal of Physics》1960,10(10):701-714
It is assumed that nucleons are described by anomalous equations for particles with spin 1/2. meson interaction with nucleons is taken in the form of pseudoscalar coupling. meson scattering on the nucleons is calculated in the first approximation of the perturbation theory. The cross-sections are dependent on several interaction constants and on one free parameter. The course of the cross-sections is determined for special values of the interaction constants and it is shown that by suitably choosing them qualitative agreement with experiment at lower energies can be obtained.
In conclusion the author thanks members of the mathematical department of the Institute of Nuclear Research for carefully carrying out the numerical calculations. 相似文献
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, 1/2. - . - . . , .
In conclusion the author thanks members of the mathematical department of the Institute of Nuclear Research for carefully carrying out the numerical calculations. 相似文献
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The possible presence of anI=0 axial vector piece in the hadronic neutral current may be detected by looking for an asymmetry in the emission of the recoil
deuterons in elastic scattering of neutrinos or antineutrinos on polarized deuterons. It is estimated that this asymmetry
could be about 40% with the incident neutrinos in the energy range of tens of MeV. 相似文献
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We apply a semiclassical approach to the scattering problem of a vibrational wave packet in the vicinity of a conical intersection of electronic energy surfaces and derive analytical expressions for the scattering matrix. The latter are valid when the scattering length that scales as square root(h) is small and a wave packet passes through the scattering region with a constant velocity. The analytical results are in excellent agreement with numerical simulations for a realistic set of parameters. 相似文献
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Volker Enss 《Communications in Mathematical Physics》1983,89(2):245-268
In quantum mechanical potential scattering theory we use selected observables to describe the asymptotic properties of scattering states for long times. E.g., we show for the position and momentum operators that for Ωε?cont(H), $$\left( {m\frac{x}{t} - p} \right)e^{ - iHt} \Psi \to 0,$$ and that the set of outgoing states is absorbing. This is obtained easily without any detailed analysis of the interacting time evolution. The class of forces includes highly singular and very long range potentials. The results may serve as an intermediate step in a proof of asymptotic completeness; as a particular application we present a simple proof of completeness for Coulomb systems. 相似文献
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J. Dorenbosch F. Udo J. V. Allaby U. Amaldi G. Barbiellini M. Baubillier F. Bergsma A. Capone W. Flegel F. Grancagnolo M. Jonker L. Lanceri M. Metcalf C. Nieuwenhuis J. Panman R. Plunkett C. Santoni K. Winter I. Abt F. W. Büsser H. Daumann P. D. Gall T. Hebbeker F. Niebergall P. Stähelin P. Gorbunov E. Grigoriev V. Kaftanov V. Khovansky A. Rosanov A. Baroncelli L. Barone B. Borgia C. Bosio M. Diemoz U. Dore F. Ferroni E. Longo L. Luminari P. Monacelli S. Morganti F. de Notaristefani L. Tortora V. Valente CHARM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,41(4):567-589
A determination of sin2 θ w based on measurements of elastic scattering of muon-neutrinos and muon-anti-neutrinos on atomic electrons is described. These purely leptonic processes were studied using the CHARM calorimeter exposed to neutrino and antineutrino wide-band beams at the CERN super proton synchrotron. A total of 83±16 neutrino-electron and 112±21 antineutrino-electron events have been detected. From the measurement of the ratio of muon-neutrino and muon-antineutrino cross-sections a value of sin2 θ w =0.211±0.037 was obtained. 相似文献