The photometric study of light scattering from the surface of alumina powder and interpretations by Hapke formula

A laboratory experiment helps to understand the light scattering property of regolith like samples with known compositions and other physical parameters. The laboratory data so obtained can be compared with the existing in situ data on celestial objects like asteroids. Further, it may be analyzed with the help of various theoretical models to understand the light scattering processes from regolith more clearly. In this work we have performed laboratory based photometry of the light scattered from the surfaces of powdered alumina (Al₂O₃) at various tilt angles of the sample and at large phase angles, with the particles having diameter 0.3 μm. The wavelength of observation was 632.8 nm. These data have been fitted by a surface scattering model originally suggested by Hapke. Instead of using empirical Henyey–Greenstein phase function to fix the values of albedo and phase function to be used within Hapke formula, we have used Mie theory for the same. This approach helped us to determine the single particle properties such as particle diameter and complex refractive index from surface scattering phase curve alone. Mie theory depends only on the size parameter X(=2π(radius/wavelength)) and complex refractive index (n, k) of the material. Since the absorption coefficient (k) for alumina is known to be very low but not exactly zero, the best fit to the experimental data was obtained by least square technique with k as a free parameter, as the other parameters are known. Finally, we compare our results with other published results and discuss the scope of application of the method we adopted.     

低温辐射计吸收腔研制

针对高灵敏度低温辐射计研制需求,提出一种低温辐射计吸收腔.设计椭球面光阑的多次反射结构,同时采用扩散焊工艺,进而实现了椭球面光阑、斜口—斜底圆柱腔和斜底面三部分的焊接成形,以此形成有效光陷阱,使入射到吸收腔中的辐射被近似完全吸收.制备具备多孔结构的碳纳米管涂层,采用喷涂为主的工艺实现腔体内壁涂层的均匀性分布.基于积分球...     

卫星光学遥感器光谱波段选择的影响因素

文章详细阐述了大气对太阳辐射在可见光 -近红外段的吸收作用和散射作用 ,并总结了可见光 -近红外波段常用的大气窗口及其透射率 ,最后 ,分析了可见光、近红外、短波红外的波段选择问题     

用固体吸附/分光光度法同时监测空气中的肼、一甲肼和偏二甲肼

介绍了用一甲肼浓缩采样采集空气中三肼混合气体,用分光光度法分别测出肼、一甲肼和偏二甲肼各组分的含量。测定结果通过标准气验证,相对误差小于１７％,各组份回收率均大于８０％。本方法适用于空气中低浓度三肼废气的测定。     

沸石分子筛对航天器分子污染物的吸附性能研究

针对空间环境中有机污染物沉积在航天器敏感部件上造成相关功能失效问题,提出一种利用沸石分子筛多孔结构在轨清除有机污染物的新方法。研究了真空环境中,Naβ、NaY、13X三种分子筛对某型号电缆真空放气产物的吸附能力,结果表明13X的吸附能力优于其它两种分子筛,饱和吸收率为14.03%。将其作为分子吸附器的吸附材料应用到航天器易污染的部位,将会有效控制航天器在轨运行的污染水平,提高可靠性。     

Tomography system for measurement of gas properties in combustion flow field

This paper describes a self-designed fiber-coupled tomography system and its application in combustion diagnostics. The tomographic technique, which combines tunable diode laser spectroscopy and algebraic reconstruction technique, enables the simultaneous reconstruction of temperature and gas concentration with both spatial and temporal resolutions. The system measures a maximum diameter of 35 cm in a circular area with a minimum spatial resolution of 1 mm×1 mm and temporal response of up to 1 kHz. Simulations validate the effects of the beam arrangement and discrete grid on reconstruction accuracy, and give the optimal beam arrangements. Experiments are made to demonstrate the tomography method, and systems are constructed in laboratory and on engineering test benches.     

低太阳吸收率加成型有机硅热控涂层的研制

为了制备低αs/εh值热控涂层，必须选择合适的粘料。系统研究了组成对加成型热控涂层性能的影响，探讨了颜料与粘粒配比、含氢硅油种类、乙烯基硅橡胶种类、Si－H与CH＝CH配比、涂布方式等对热控涂层太阳吸收率（αs）、红外辐射率（εh）及αs/εh影响规律。     

非均匀磁化等离子体层的电磁特性分析

基于分层传播原理提出了一种计算电磁波在非均匀磁化等离子体层中反射率和吸收率的模型,并数值分析了等离子体密度与碰撞频率,以及背景磁场强度对电磁波的反射和吸收特性的影响.研究表明:该法所得结果与文献的传播矩阵(SMM)法一致.数值分析发现:低密度高碰撞频率等离子体可减少等离子体层对入射波的功率反射;高密度高碰撞频率等离子体可改善其对入射波的功率反射宽频带吸收特性;背景磁场强度可明显改变等离子共振吸收频段.     

铝粉中微量铜的分光光度法测定

介绍了用BCO分光光度法对铝粉中微量铜的测定。该方法简便、精密度、灵敏度高。     

基于TDLAS的电弧风洞流场Cu组分监测

电弧风洞是进行防热材料和防热结构考核与研究的必要设备，也是高超声速地面试验能力的重要组成部分，但电弧加热器的电极烧蚀会导致较为严重的流场污染，影响试验准确性。利用可调谐二极管激光吸收光谱技术（TDLAS），通过对20 MW级片式电弧加热器内部流场中Cu原子809.25 nm跃迁谱线进行实时测量，研究了电弧风洞流场中Cu污染情况和电极烧蚀情况。在获得Cu原子该谱线低能态数密度基础上，估算了运行功率分别在7.3、8.7、10.0和11.7 MW时流场中Cu组分（原子态和离子态）总数密度平均为10.6×10¹³、11.2×10¹³、11.7×10¹³和16.4×10¹³ cm^-3，同时得到平均电极烧蚀率约为1.65×10^-5 g/C。试验还发现，TDLAS信号在高温流场建立阶段起伏变化明显，并且在功率跃变时也会出现突然增强而后迅速回落的现象，表明电弧抖动会使电极烧蚀严重加剧。