共查询到20条相似文献,搜索用时 46 毫秒
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分布布喇格反射镜的反射特性 总被引:2,自引:1,他引:1
采用等效法布里珀罗(FP)腔方法对分布布喇格反射镜(DBR)的特性进行了研究,计算并讨论了上下两层DBR结构非对称模型反射率的变化.设计了DBR反射镜的反射谱中心波长为850nm的结构.随着DBR周期数的增加,腔反射率峰值逐渐增加.上下两层DBR反射镜的厚度由反射率和中心波长决定.实验表明,下DBR的周期数为30对左右,上DBR的周期数为20对左右,易实现激光输出.非对称的双层DBR的反射特性表明理论计算与实验结果基本一致. 相似文献
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提出了活化法测量DD中子产额的实验方法,该方法可提高DD中子产额测量的精度。方法基于铟同位素115In与DD中子的非弹性散射反应,活化反应释放的射线被HPGe探测器记录,根据活化系统标定灵敏度推算出中子产额。分析了探测器记录的活化射线数与中子产额间的关系。介绍了一套活化测量的系统设计。通过蒙特卡罗方法模拟了活化样品出射的射线数与样品厚度的关系,模拟结果表明:样品厚度取为1 cm可兼顾活化效率和测量精度。在加速器上对铟活化样品进行了标定实验,实验结果表明:在聚变中子产额大于2109的实验中可使用铟活化诊断方法,中子产额测量的相对标准误差在10%以内。随着聚变中子产额的不断提高,铟活化测量中子产额的精度可进一步提高。 相似文献
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提出了一种用于高功率微波武器的等离子体通道天线(PCA),计算了该天线的辐射方向图。推导出了一般性天线的辐射方向函数;建立了PCA的近似电磁模型;给出了圆坐标系下PCA和周围空气中的电磁场,利用边界条件得出了PCA的色散方程,求出PCA的表面波波矢。重点讨论了PCA的辐射场随等离子体密度、天线长度、半径的变化,证实了PCA方向图的可控性。 相似文献
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Kalluri D.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(1):11-16
The reflection by a suddenly created plasma half-space of a time-harmonic plane electromagnetic wave propagating in free space is considered. The problem involves a temporal discontinuity, a spatial discontinuity, and a dispersive medium. The steady-state solution is obtained by considering the basic features of the scattering processes due to each of the discontinuities in terms of analogous transmission-line models. The electric field of the reflected wave consists of two components. One component (called component A) is of the same frequency as the incident wave frequency and is due to the spatial discontinuity. The other component (called component B) is of a different frequency and arises because of the temporal discontinuity. The B component is damped out even if the plasma is only slightly lossy. The damping rate of the B component is calculated. The transient solution is obtained through the use of Laplace transforms. The solution is given in terms of Bessel-like functions. The limiting value of this solution is shown to agree with the steady-state solution. Numerical results illustrating the transient effects are for two typical cases 相似文献
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A. N. Chernikov V. N. Trofimov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(5):956-960
A helium-3 adsorption refrigerator cooled with a pulse-tube cryocooler is developed. The refrigerator has two stages of adsorption pumping. The first stage is designed for the condensing and pumping of helium-4, whose cooling capacity is used for the condensation of helium-3. The second stage is designed for pumping helium-3. The final temperature reached by the refrigerator is 0.305 K. This temperature is retained for at least 24 h. The time required for helium recondensation and the obtainment of low temperature is 1.5 h. The cryostat is a self-contained instrument, as it contains no external gas-supply pipelines and the working gas is stored directly within the working volume of the refrigerator. The work is performed in the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research. 相似文献
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聚合硫酸铁絮凝剂中痕量镉分光光度法测定研究 总被引:2,自引:0,他引:2
本文研究了分光光度法测定聚合硫酸铁絮凝剂中痕量镉的新方法并探讨了显色反应机理。本法是利用分光光度法测定聚合硫酸铁絮凝剂中痕量镉。显色剂为罗丹明B和碘化钾。表面活性剂为聚乙烯醇(PVA)。光度显色反应灵敏度高 ,其最大吸收波长为 60 7nm。表观摩尔吸光系数为 4 99× 1 0 5L·mol- 1 ·cm- 1 。桑德尔灵敏度为 2 2 5× 1 0 - 4 μgCd(Ⅱ )·cm- 2 。镉含量在 0~ 1 5 μg·2 5mL- 1 范围内服从比尔定律。回收率为 96%~ 1 0 5 %。方法操作简便 ,不需要萃取分离 ,可在水相中直接测定 ,故大大简化了操作手续。用本法测定了聚合硫酸铁絮凝剂中的痕量镉 ,得满意效果 相似文献
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H. Trabelsi T. Sghaier M.S. Sifaoui 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,93(4):415-428
A modified discrete ordinates method (DOM) is used in spherical participating media. The radiative intensity is broken up into two components. One component is traced back to the enclosure's source. It is called direct intensity. The other component is rather traced back to the contribution of the medium itself. It is called diffuse intensity. Thus, the radiative transfer equation (RTE) is transformed into two simultaneous equations: a direct RTE and a diffuse RTE. The direct RTE is solved analytically. The diffuse RTE is solved numerically using the DOM. The streaming angular derivative term appearing in spherical geometry is modeled by making use of the Finite Legendre Transform. We study a pure radiation transfer problem between two concentric spheres. The medium is assumed to be gray and isotropically scattering. The limiting spheres are considered to be opaque, gray, diffusely emitting and diffusely reflecting with uniform emissivity over each surface. The obtained results are compared with available cases reported in the literature. In particular, relative importance of the direct radiation in optically thin media is studied. 相似文献
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I.IntroductionTheprob1cmofsuppressingstrongpointinterferencesourceisavcryimportantthesisinsonardesign.Fortheana1ogsonar,thesolutionofthisprob1emisquitedifficu1t.Untilthedevelopmentofdigitalsonar,thereissomerescarchreportsaboutsuppressingstrongpointin-terferencesource.Theear1ierworkin1969,dedicatcdbyV.C.Anderson,istheconccptofDICANNE(DigitalInterfcrcnceCance1lingAdaptiveNu1lNetworkEquipment)['l.Thisisadoublecompensatormulti-bcamsystcm.Oneisusedtoformintcrfercncebeamandanothcrisusedtofor… 相似文献
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M. I. Ryazanov A. A. Tishchenko 《Journal of Experimental and Theoretical Physics》2006,103(4):539-545
The dielectric properties of a quasi-two-dimensional molecular monolayer are analyzed. The dielectric function of the monolayer is expressed in terms of molecular polarizability and monolayer characteristics. The expression is analogous to the well-known Clausius-Mossotti equation for three-dimensional systems. The response of the monolayer to an external field is calculated. The case of a planar array of nanoparticles is also considered. The solution is obtained in the framework of a local-field theory. 相似文献
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提出了一种用于高功率微波武器的等离子体通道天线(PCA),计算了该天线的辐射方向图。推导出了一般性天线的辐射方向函数;建立了PCA的近似电磁模型;给出了圆坐标系下PCA和周围空气中的电磁场,利用边界条件得出了PCA的色散方程,求出PCA的表面波波矢。重点讨论了PCA的辐射场随等离子体密度、天线长度、半径的变化,证实了PCA方向图的可控性。 相似文献
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采用压力传感器和温度传感器,通过数据接口由计算机实时采集数据并进行处理,观察到气体的热力学过程的状态变化,测得了氧气的摩尔热容量CV随着温度的变化.结果表明氧气的CV随温度的变化有一突变,这与能量均分定理所描述的基本一致,氧气的振动自由度被冻结的温度在240K左右. 相似文献