Modeling Study on the Characteristics of Laminar and Turbulent Argon Plasma Jets Impinging Normally upon a Flat Plate in Ambient Air

Modeling study is performed to compare the flow and heat transfer characteristics of laminar and turbulent argon thermal-plasma jets impinging normally upon a flat plate in ambient air. The combined-diffusion-coefficient method and the turbulence-enhanced combined-diffusion-coefficient method are employed to treat the diffusion of argon in the argon-air mixture for the laminar and the turbulent cases, respectively. Modeling results presented include the flow, temperature and argon concentration fields, the air mass flow-rates entrained into the impinging plasma jets, and the distributions of the heat flux density on the plate surface. It is found that the formation of a radial wall jet on the plate surface appreciably enhances the mass flow rate of the ambient air entrained into the laminar or turbulent plasma impinging-jet. When the plate standoff distance is comparatively small, there exists a significant difference between the laminar and turbulent plasma impinging-jets in their flow fields due to the occurrence of a large closed recirculation vortex in the turbulent plasma impinging-jet, and no appreciable difference is found between the two types of jets in their maximum values and distributions of the heat flux density at the plate surface. At larger plate standoff distances, the effect of the plate on the jet flow fields only appears in the region near the plate, and the axial decaying-rates of the plasma temperature, axial velocity and argon mass fraction along the axis of the laminar plasma impinging-jet become appreciably less than their turbulent counterparts.

大功率高重复频率准分子激光器单元技术及元器件

<正> 由中国科学院力学研究所承担的“大功率高重复频率准分子激光器单元技术及元器件”系国家重点科技攻关项目,已通过中科院和国家教委联合组织的鉴定会。该项目包括三项具体研究成果,即磁脉冲压缩器、高重复频率大电流开关、数字式高电压表。

强红外激光引起BCl_3可见荧光的动力学研究

用TEA CO_2激光辐照纯BCl_3气体,观察到可见荧光具有多种过程。系统地测量了可见荧光的空间、时间、光谱结构,以及它们随激光能量、BCl_3气压等参数的依赖关系。用简化碰撞动力学模型讨论了BCl_3可见荧光过程,得到有效振动温度、可见荧光强度的分析表达式和ρT_延≌C/K(T_ν)的简单关系。理论与实验结果一致。

HF化学激光放大器的交叉弛豫动力学研究

在低气压超声速cwHF化学激光放大器中，假设平动和转动非平衡交叉弛豫同时起作用。对于气流介质的层流和湍流扩散混合两类流动模型，分别导出了饱和增益谱的表示式，并进行了数值计算。计算结果表明，湍流扩散混合模型与实验结果符合得更好。

Self-focusing, Raman, and modulation instability of shaped relativistic laser pulse in plasmas

The interaction of shaped laser pulses with plasmas is studied in a strict theoretical framework without adopting the slow-varying envelope approximation (SVEA). Any physical quantities involved in the interaction are denoted as a summation of different real quantities of respective phases. The relationships among the phases of those real quantities and their moduli are strictly analyzed. Such strict analyses lead to a more exact equation set for the three-dimensional envelope of the laser pulse, which is not based on SVEA. Based on this equation set, self-focusing, Raman, and modulation instabilities could be discussed in a unified framework. The solutions of this equation set for the laser envelope reveal many possible multicolor laser modes in plasmas. The energy and the shape of a pulse determine its propagation through plasmas in a multicolor mode or in a monochromic mode. A global growth rate is introduced to measure the speed of the transition from the monochromic mode in vacuum to a possible mode in plasmas. (c) 2006 American Institute of Physics.

Inverse symmetric Dammann gratings

Inverse symmetric Dammann grating is a special grating, whose transition points are reflection symmetric about the midpoint with inverse phase offset in one period. It can produce even-numbered or odd-numbered array illumination when the phase modulations are pi or a specific value. Numerical solutions optimized by the steepest-descent algorithm for binary phase and multilevel phases with splitting ratio from I x 4 to 1 x 14 are given. Fabrication of 1 x 6 array without the zero-order intensity and 1 x 7 array with the zero-order intensity are made from the same amplitude mask. A 6 x 6 output without the crossed zero-orders was achieved by crossing two one-dimensional 1 x 6 inverse symmetric Dammann gratings. This grating may have potential value for practical applications. (C) 2008 Elsevier B.V. All rights reserved.

氧分压对电子束蒸发SiO2薄膜机械性质和光学性质的影响

采用ZYGO MarkⅢ-GPI数字波面干涉仪、NamoScopeⅢa型原子力显微镜对不同氧分压下电子束蒸发方法制备的SiO2薄膜中的残余应力及表面形貌进行了研究，结果发现：随着氧分压的增大，薄膜中的压应力值逐渐减小，最后变为张应力状态；同时薄膜的表面粗糙度也随着氧分压的增大而逐渐增大，另外，折射率对氧分压也非常敏感，随着氧分压的增大呈现出了减小的趋势，这些现象主要是由于氧分压的改变使得SiO2薄膜结构发生了变化引起的。

平面行星夹具的物理气相沉积均匀性计算

建立了平面行星夹具薄膜淀积无量纲模型。通过对蒸发源位置LIH、行星主轴与副轴距离PIH、夹角倾角A以及蒸发源蒸汽发射特性N等因素的分析，得到了典型径向理论均匀的优化几何配置．并从优化几何配置的膜料效率、角向均匀性和膜厚分布对蒸发源蒸汽发射特性变化的敏感性方面评价优化结果，得到了最优化设计区域．结果表明，优化配置的LIH＋PIH小，则角分布差异小；LIH＋PIH和A小，则膜料效率高；L〈P，A=15°时，优化配置对N变化最不敏感；L〉P时，由N变化引起的典型径向分布变化小于0．5％．

一种吸湿保湿剂及其制备方法

本发明涉及日化领域及医药行业，具体讲是一种多糖类吸湿保湿剂及其制备方法。所述吸湿保湿剂采用羧甲基透明质酸。其由按摩尔质量比为1：4-6的经碱性异丙醇溶液溶胀的透明质酸与氯乙酸在过量的碱性异丙醇溶液中以35℃—75℃条件下反应1-5h,而后抽滤、烘干即得。本发明通过有效的合成手段得到的羧甲基透明质酸，生产成本提高甚微，而吸湿保湿性能提高明显，通过提高其活性，从而间接地降低生产成本。从而本发明将羧甲基透明质酸作为吸湿保湿剂其吸湿保湿性能高于透明质酸，而且透明质酸羧甲基化的成本低、产率高。

大熊猫遗传多样性的蛋白电泳研究

大熊猫(Ailuropoda melanoleuca)由于数量稀少,分布地区狭窄而割裂,食物单调,生殖力低下等原因而面临濒危境地.以往的工作多集中于野外的生态、行为、数量分布、群体年龄结构、食物等方面,对大熊猫群体遗传结构或群体遗传特征如近亲交配系数等我们知之甚少.众所周知,大熊猫的生存力很弱,尤其表现于其生育力低下,产仔率较一般哺乳动物低,幼仔死亡率高达60%;雄体的精液质量差,畸形精子率达29.7%;雌体存在延迟着床的生理现象.