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钾原子中多种受激辐射参与的混频过程 总被引:2,自引:1,他引:1
当双原子共振激发钾原子于6S能级时,由光泵受激辐射和电离复合受激辐射参与的六波或四波混频,产生了位于紫外和紫区的诸多相干辐射、文中对多种混频机制进行了分析和讨论,并对所测得的相干辐射线进行了标识. 相似文献
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本文报道锂蒸气中由双光子泵浦所产生的位于紫外、可见和红外区的相干和受激辐射。包括:由一特殊六波混频过程产生的在1.03μm附近的可调谐相干辐射,由锂分子双光子离解或原子串级跃迁产生的波长为812.6nm的受激辐射,以及由四波混频产生的位于323.3nm和670.8nm的相干辐射。
关键词: 相似文献
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本文报道以等频二步激发钠分子-原子系统,观测到强度随泵浦光的调谐而呈振荡变化的3P—4P受激喇曼散射,以及对应4D—4P和4F—3D跃迁的红外受激辐射和由四波混频产生的816.8~822.1nm区内可调谐相干辐射。文中对这些过程进行了分析讨论。 相似文献
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双光子激发钠原子所产生的级联受激辐射光子与入射激光双光子可产生光波混频。实验共观测到十一条六波混频与十条四波混频谱线。理论分析表明脉冲激光泵浦下的光波混频过程仍可用稳态近似计算混频光强。非线性极化系数X不仅与基态布居数也与激发态布居数有关。X的共振增强效应对获得强混频输出有重要作用。 相似文献
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本文首次报道了由钾分子-原子系统的混合激发和碰撞能量转移过程产生4F→3D受激辐射以及由钾原子的4S→4F偶极禁戒双光子共振产生4F→3D受激辐射和四波混频的研究结果。 相似文献
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研究了受强缀饰场作用的五能级原子系统所产生的多波混频共存特性.研究发现,通过调节激光束方向,沿同一方向出射的八波混频、双缀饰四波混频和单缀饰六波混频信号因共用能级的原子相干产生而出现竞争现象,通过控制缀饰场减弱四波混频和六波混频信号强度,可以达到增强八波混频信号的目的.还对级联和并联两种不同缀饰方式下双缀饰四波混频过程的差别进行了详细分析.
关键词:
双缀饰四波混频
单缀饰六波混频
八波混频
抑制增强 相似文献
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A flow control study of a supersonic mixing layer via NPLS 总被引:1,自引:0,他引:1
The flow control of a supersonic mixing layer was studied in a supersonic mixing layer wind tunnel with convective Mach number
(Mc) at 0.5. The passive control of the mixing layer was achieved by perturbation tapes on the trailing edge of the splitter
plate. The control effects of 2D and 3D perturbation tapes with different sizes were compared. The mixing layer was visualized
via NPLS, and the transient fine structures were identifiable in NPLS images, which were used to analyze the effects of flow
control. The results show that the 2D tapes can enhance the 2D characteristic of the mixing layer, delaying mixing layer transition;
and the 3D tapes can enhance the 3D characteristic of the mixing layer, advancing mixing layer transition. 3D structures of
the mixing layer were visualized, and the H-type Λ vortexes were found with 3D tapes control. 相似文献
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Jing-Song Wen Shao-Kuo Lei Yao-Huan Liang Xiang-Fang Peng Jin-Ping Qu 《Journal of Macromolecular Science: Physics》2014,53(2):358-369
The polymer vane extruder, whose plasticating and conveying theory is based on elongational rheology, is a significant development in plastic processing equipment. As a result of its unique structure, it is desirable to use numerical simulation to study it. The results can be useful to set process parameters and optimize its structure. In this paper, numerical simulation of the mixing characteristics of the vane extruder was performed with the finite element computational fluid dynamics program POLYFLOW. To visualize the mixing process of the melts in a vane extruder based on the calculation of the transient flow, a particle tracking method was applied. By using the statistical post-processor program POLYSTAT, dispersive mixing and distributive mixing characteristics were evaluated in terms of shear rate, stretching rate, mixing index, and time average mixing efficiency. The simulation results showed that strong stretching existed in the vane extruder demonstrating that the vane extruder generated a more appropriate flow than a common twin-screw extruder to break material particles into smaller ones. The probability functions of mixing efficiency showed that the position near the outflow had the highest mixing efficiency. Furthermore, the time average mixing efficiency of most particles in the vane extruder were larger than that in a twin-screw extruder, indicating that in the vane extruder more mechanical energy was used to generate stretching. 相似文献
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提出了在圆形滚筒内设置十字形内构件的增混方式,并采用离散单元方法对设置不同大小内构件的滚筒内非等粒径二元颗粒体系的混合进行了数值模拟试验.通过模拟结果重点分析了内构件对混合的影响,讨论了内构件的尺寸对混合效果的作用,分析和探讨了滚筒内构件对二元颗粒体系的增混机理.研究发现,当滚筒内无内构件时,对流、扩散和离析三种作用机制对颗粒体系的混合和分离都起到了重要作用;当滚筒内含内构件时,颗粒的混合则只受到颗粒对流和扩散机制的作用,而颗粒的离析效应得到了很大程度的抑制.十字形内构件很大程度上会破坏滚筒内的自由表面流,从而使发生在自由表面流中的颗粒分离不能发生,最终可有效地增加颗粒之间的混合.对于采用在滚筒内设置十字形内构件的方式来增加颗粒间的混合,存在一个最优的内构件尺寸,内构件过小或过大都不利于颗粒间的混合.
关键词:
分离
混合
离散单元法 相似文献
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Naoki Kurimoto Yu Saiki Kristian Angele Yuji Suzuki Nobuhide Kasagi 《Journal of Turbulence》2013,14(5):411-441
Active mixing control of a methane/air isothermal coaxial jet was achieved using micro magnetic flap actuators arranged on the inner surface of the outer annular nozzle. The spatio-temporal evolution of vortical structures and the scalar mixing were studied through the particle image velocimetry and planar laser-induced fluorescence methods. In contrast to studies on jet control using acoustic forcing, the mechanical movement of the flap directly generated large-scale intense vortices. The mixing was enhanced significantly by the vortices formed in the inner shear layer, although the control input was given to the outer shear layer. It was found that the primary vortex rings dominated the near-field mixing, while streamwise vortices were responsible for the downstream mixing. It was also demonstrated that the radial range of the inner fuel transportation could be manipulated flexibly by adjusting the shedding interval of the vortices. Especially, the mixing was enhanced most significantly when the primary vortices were most densely populated near the nozzle exit at the control Strouhal number of unity. 相似文献
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合成气压缩机循环段由于高压和流动空间限制,难以测量内部流动参数,导致无法从工程上判断循环段流动性能。为此本文建立了高压缸出口段、混合腔和循环段叶轮流道模型,采用合成气物性,在约14.4 MPa(A)的高压进口条件下,使用CFD的方法研究了循环段内部流动混合发展规律。选取常用的七种损失模型评估了叶轮内损失,并研究了混合腔对下游叶轮性能的影响。结果表明混合腔内呈现出明显的二次流动,随着流动向下游发展,流场变得越来越均匀。混合腔损失、叶片负载损失和尾迹损失是主要的损失源。由于上游混合腔的影响,带有混合腔的叶轮的压比和效率低均低于单独均匀进口叶轮情况,且其工况范围更窄。本文的结果可为新型合成气压缩机产品的设计提供参考。 相似文献
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氧碘混合过程是化学氧碘激光器(COIL)中的一个重要步骤,氧碘混合质量直接决定着COIL的运行效率和光束质量。采用化学荧光法,研究了两种不同结构的扰动翼片组对COIL超音速平行流混合过程的影响。实验结果表明,1#扰动翼片组对氧碘超音速平行流的混合增强效果明显,其荧光区达到主气流中心线所经历的流向距离大幅缩短,碘解离区内的荧光区与测试区的面积比相对于无混合扰动时提高了4.2倍;采用2#翼片组扰动混合时,流向距离值进一步缩短了40%~60%,碘解离区内的面积比值又提高了20%~40%。氧发生器有/无主载气条件(2#翼片组)下的混合过程比较显示后者混合效果更好。 相似文献
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Hui Sun Jie Feng Jiajun Wang Bin Yu Jing Sheng 《Journal of Macromolecular Science: Physics》2013,52(2):328-337
Isotactic polypropylene/poly(cis-butadiene) rubber (iPP/PcBR vol%: 80/20) blends were prepared by melt mixing with various mixing rotation speeds. The effect of mixing technique on microstructure and impact property of blends was studied. Phase structure of the blends was analyzed by scanning electron microscopy (SEM). All of the blends had a heterogeneous morphology. The spherical particles attributed to the PcBR-rich phase were uniformly dispersed in the continuous iPP matrix. With increase of the mixing rotation speed, the dispersed phase particle's diameter distribution became broader and the average diameter of the separated particles increased. The spherulitic morphology of the blends was observed by small angle light scattering (SALS). Higher mixing rotation speed led to a more imperfect spherulitic morphology and smaller spherulites. Crystalline structure of the blends was measured by wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS). The introduction of 20 vol% PcBR induced the formation of iPPβ crystals. Higher rotation speed led to a decrease in microcrystal dimensions. However, the addition of PcBR and the increase of mixing rotation speed did not affect the interplanar distance. The long period values were the same within experimental error as PcBR was added or the mixing rotation speed quickened. The normalized relative degree of crystallinity of the blends slightly increased under lower rotation speeds (30 and 45 rpm) and decreased under higher rotation speeds. The notched Izod impact strength of the blends was enhanced as a result of the increase of mixing rotation speed. 相似文献