Integral radiant emissivity of tungsten in the 1200–2800°K temperature range

Data on the spectral radiant emissivity of tungsten are used to compute the integral radiant emissivity of this element in the 1200–2800°K temperature range.The authors are grateful to G. P. Konyukhov and the Ural-2 programming staff for carrying out the computations.     

CFETR内冷屏结构方案初探

基于现有冷屏结构,结合CFETR聚变堆装置的结构特点,提出了一种沿冷却板厚度方向钻冷却通道的深孔结构方案.对内冷屏各部件设计了并联加串联的特殊流道,采用有限元法计算了该方案内冷屏各部件的温度分布.结果表明,采用深孔法冷却方式,冷屏温度分布更均匀,降温效果更好.在输出辐射功率相近的条件下,深孔法的冷却方式可将表面辐射率上...     

纯钨红外光谱发射率特性研究

光谱发射率是一个重要的热物性参数,在辐射测温、热传输计算等领域有着广泛的应用。钨作为一种重要的金属,关于其光谱发射率的研究报道较少。利用黑体炉、傅里叶红外光谱仪、加热装置和光学系统搭建了一套能量对比法光谱发射率测量装置,该装置能够测量3~20μm的光谱发射率,测量装置的整体不确定度优于5%。利用该装置测量了纯钨在4个温度点(573, 673, 773和873 K)的法向光谱发射率,重点探讨了氧化、温度、波长和加热时间对纯钨光谱发射率的影响。研究结果表明:纯钨在表面未氧化的情况下,光谱发射率在几个温度点的变化规律基本一致,且数值相差较小,而当其表面发生氧化后光谱发射率迅速增加,在某些波长处出现了强烈的振荡。表面未氧化时纯钨的光谱发射率受温度的影响较小,随着温度的增加仅出现微小的增加,但是当表面发生氧化后,随温度的升高而迅速增大。纯钨的光谱发射率整体上随着波长的增加而减小,但是当表面发生氧化后,由于表面氧化膜与钨金属基底发生干涉效应,在4, 9, 12.5和16.5μm处均出现了峰值。在573和673 K,纯钨的光谱发射率随着加热时间的增加无明显变化。然而,随着温度的升高,在773和873 K时,光谱发射率随着加热时间增加而增大,在773 K时光谱发射率随加热时间的增加增幅较大,因为在该温度点,纯钨表面刚开始发生氧化,氧化速率较大,在873 K时光谱发射率随加热时间的增加增幅较为平缓,并且随着加热时间的增长呈现稳定的趋势。综上,纯钨的光谱发射率在温度较低和表面未氧化时较为稳定。随着温度的升高,当表面发生氧化后,光谱发射率迅速增大,并且在多个波长位置出现了强烈的振荡。由此可见,纯钨光谱发射率受温度、波长、加热时间的影响较大,在实际应用过程中,特别是在辐射测温过程中,如果把纯钨的光谱发射率看做常数将会带来较大的测量误差。该研究将进一步丰富钨的光谱发射率数据,并为其在科学研究和应用中提供数据支持。     

Infrared radiant emissivities of ceramics with spinel structure

The infrared radiant ceramic materials were prepared by calcination at high temperature. Based on the study of infrared radiant emissivity and X — ray diffraction spectra, the results indicate that spinel structure possesses the higher infrared radiant emissivity. The reason of the higher infrared emissivity of the spinel structure has been explained according to the Group Theory.     

瞬时多光谱辐射测温方法

采用光学多道分析仪测量了溴钨灯和氙闪光灯的辐射光谱,给出了一种辐射测温的数据处理方法,即在Planck灰体模型假定的基础上,进一步考虑发射率ε与波长的多项式依赖关系以及辐射本底对实验结果的影响,建立相应的多光谱测温数据处理方法,并用溴钨灯和氙闪光灯的实测光谱对其进行了验证.结果表明:对于连续光谱且发射率逼近黑体,可以假定发射率为常量,按Planck灰体模型处理;对于非连续光谱,当电流密度不高时,发射率与波长依赖关系较强,可以根据发射率与依赖波长的多项式关系并结合0＜ε＜1限定按Planck灰体模型处理.     

辐射器漫反射定向管表面热辐射方向性

为了得到辐射能的方向分布特性,利用蒙特卡罗法,研究了定向管内壁面为不等温灰体、其底部假想圆型辐射器为黑体时,管内壁发射率、管长与半径比、管内空气流速等参数的变化对管口表面当量定向发射率的影响,计算结果表明:管长与半径比增加,管口表面较大的当量定向发射率向小角度的天顶角方向移动,空气流速仅影响当量定向发射率数值大小。     

基于激光旋转加热的非导电材料高温光谱发射率测试方法与装置

光谱发射率是表征材料热物理性能的重要参数。对于非导电材料的高温光谱发射率测试,一般采用高温加热炉加热或辐射加热的方式来进行发射率测试,存在的问题是采用高温石墨炉加热时,样品可能会与高温石墨发生化学反应,从而破坏材料原有物性;采用辐射加热,一般是单向静止加热,会存在样品温场梯度非均匀分布的问题。基于激光旋转加热和样品/黑体整体一体化设计,提出了一种“样品动中测”的非导电材料高温光谱发射率测试新方法,建立了相应的测量模型,突破了传统的 “样品静中测”的局限,样品与参考黑体共形一体化设计,采用微区域光谱辐射成像方法,同时测量参考黑体和样品的光谱辐射能量与温度。建立了激光旋转加热状态下的热传导方程,对典型样品材料的温度分布进行了仿真计算,结果表明旋转样品温场分布较为均匀,分析了温场分布与红外光谱发射率测量误差间的关系,给出了适用于本测试方法的材料的热导率下限值。基于该方法,搭建了相应的测量装置,对典型材料碳化硅在1 000 K时的光谱发射率进行了测试,在4 μm处对各个典型高温温度点的光谱发射率进行了测试,得到了碳化硅材料在红外波段的光谱发射率波长变化和温度变化规律特性。与国外的测量结果进行了比对,结果较为一致,验证了激光旋转加热光谱发射率测试方法的可行性。采用此方法,不破坏样品本身的理化特性,样品加热升温速度快,测量温度范围上限高,有效减小了激光静止单向加热带来的温度不均匀性,可同时测量出样品和参考黑体的光谱辐射亮度及温度,无需另外再设计标准高温黑体,解决了现有非导电材料高温光谱发射率测试中非均匀加热和辐射能量同步比对测量的问题,可应用于多种非导电材料高温光谱发射率的测试。     

Experimental and theoretical studies of the evolution of normal spectral emissivity during successive steps of tungsten oxidation

We studied the influence of oxidation on the normal spectral emissivity of tungsten in the wavelength range 1–10 μm under well-controlled conditions. The optical measurements have been performed under an oxygen pressure of 1.3 Pa and in the temperature range 800–1000 K, until the oxide was thick enough to be opaque to the radiation concerned. The experimental curves of emissivity versus exposure show an induction time followed by a maximum before a steady-state value is reached. In conjunction with a growth model, supported by X-ray diffraction and electron microscopy studies, we propose an optical model of heterogeneous media which correctly accounts for the observed variations of emissivity during the whole reaction. By inserting the optical constants of the various media into this model, we show that it is possible to characterize, by emissivity the morphology of the oxide on the surface during the reaction, until the oxide is thick enough to be opaque.     

Using spectral distribution of radiance temperature and relative emissivity for determination of the true temperature of opaque materials

A method for determining the thermodynamic (true) temperature of opaque materials by the registered spectrum of thermal radiation under the conditions when we do not know emissivity of a free-radiating body is presented. A special function, which is a product of relative emissivity of tungsten by the radiation wavelength, was used as the input data. The accuracy of results is analyzed. It is shown that when using relative emissivity, the proposed algorithm can be used both within the range of applicability of the Wien approximation and the Planck formula.     

Experimental study of the relationships between the spectral emissivity of brass and the temperature in the oxidizing environment

Effect of surface oxidization on the spectral emissivity of brass is studied over the temperature range from 800 to 1070 K at the wavelength of 1.5 μm. The temperature of brass surface is measured by averaging the two R-type platinum–rhodium thermocouples. The radiant energy emitted by the brass surface is received by an InGaAs photodiode detector. Two kinds of relationships between the spectral emissivity and the temperature are investigated in the oxidizing environment at the elevated temperature. One is the variation of spectral emissivity with the heating-duration time at the given temperature. The other is the variation of spectral emissivity with the temperature at the given heating-duration time. The interference effect of radiation coming from the brass surface and coming from the oxidization film is discussed when the oxidation film on the surface is grown. The resonant structures of spectral emissivity are observed during the whole heating period, in particular at the early stage of heating duration. The analytic formula of spectral emissivity versus the temperature is derived at the heating-duration time of 30, 60, 90, 120, 150, 180, 210, 240, 270 and 300 min, respectively. The conclusion is obtained that coefficients of analytic expressions between the spectral emissivity and the temperature are different from each other for the experimental results obtained at the different heating-duration time, though the polynomial functional form is suitable to fit all the measurements obtained in the present work.     

冲击压缩下氩气辐射特性初步研究

 用二级轻气炮加载方法把平面钨飞片加速到1.78 km/s、2.00 km/s和2.76 km/s,对封装有氩气的铝材料靶盒进行碰撞,由此产生的平面冲击波加热氩气样品。通过光纤传输、六通道瞬态光学高温计和示波器系统记录冲击氩气的高温辐射历史,从而测量出气体中的冲击波速度,并观察出随冲击强度的逐渐增大时氩气发光特性的变化规律：冲击压缩下波后氩气的光辐射强度随时间变化,信号曲线从直线变为指数曲线。在一维冲击波和局域热动平衡假设下,通过简单的理论计算和分析解释了实验现象和相关的辐射机制。     

Erhöhung der Feldelektronen-Emission von Wolframspitzen durch Aufdampfen von Beryllium

The mean work function of tungsten determined from Fowler-Nordheim plots can be reduced from 4.5 to 2.5 eV by depositing a thin layer of evaporated beryllium and subsequent thermal treatment at 800 °C in a vacuum of 10^?7 to 10^?10 Torr. Electron and ion field emission patterns of tungsten tips with and without beryllium demonstrate the effect of the beryllium deposit. For an application of the tungsten tips with beryllium, the excellent stability and the high emissivity at low voltages are of interest.     

双波长高精度红外测温仪

利用双波长红外测温方法,通过黑体红外辐射曲线中双波长等比吸收的原理消除了由于辐射环境中水蒸气等外界吸收原因造成的单波长红外测温仪中的测量误差,实现更稳定的高精度红外测温.该方法绕开了传统红外测温方法中"辐射率修正困难"的问题.同时利用此红外测温仪器改进了金属钨电子逸出功测量实验.     

Determining the temperature of an opaque object by its thermal radiation spectrum: forms of initial data presentation and methods

Spectral distributions of intensities, relative emissivity, and inverse radiance temperatures of an opaque, free-radiating object in a condensed state are used as the initial data. The methods of determining the thermodynamic (true) temperature corresponding to these distributions, when object emissivity is previously unknown, are considered. The advantages and disadvantages of each method and corresponding form of an initial data presentation are discussed. It is shown that the spectral distribution of inverse radiance temperatures gives the greatest information about the true temperature and emissivity of the measured object. The estimates of the temperature range to which the true temperature belongs are given based on the known experimental data for tungsten. The methods for additional verification of reliability of the obtained results are presented.     

阳加速器钨丝阵内爆软X光功率辐射特性

介绍了在阳加速器上进行的系列W丝阵Z箍缩物理实验,实验中阳加速器Marx充电电压60 kV,负载电流输出0.85~1.00 MA,电流上升时间75~90 ns（10%~90%）;进行软X光辐射功率测量的主要仪器是软X光闪烁体功率计,其核心部件为对50~1800 eV X光具有平响应特性的蓝光闪烁体。给出了系列W丝阵Z箍缩实验软X光辐射功率测量结果,从软X光辐射输出随丝阵负载参数（包括丝阵直径、长度、丝数）变化关系讨论了钨丝阵内爆辐射特性,给出了阳加速器上各负载参数优化的结果:丝阵直径Ф8 mm,丝阵长度15 mm,丝数24。同时对软X光辐射的空间分布特性进行了初步的探讨,给出了辐射功率在负载的轴向和径向的分布。     

阳加速器钨丝阵内爆软X光功率辐射特性

介绍了在阳加速器上进行的系列W丝阵Z箍缩物理实验,实验中阳加速器Marx充电电压60 kV,负载电流输出0.85~1.00 MA,电流上升时间75~90 ns（10%~90%）;进行软X光辐射功率测量的主要仪器是软X光闪烁体功率计,其核心部件为对50~1800 eV X光具有平响应特性的蓝光闪烁体。给出了系列W丝阵Z箍缩实验软X光辐射功率测量结果,从软X光辐射输出随丝阵负载参数（包括丝阵直径、长度、丝数）变化关系讨论了钨丝阵内爆辐射特性,给出了阳加速器上各负载参数优化的结果：丝阵直径Ф8 mm,丝阵长度15 mm,丝数24。同时对软X光辐射的空间分布特性进行了初步的探讨,给出了辐射功率在负载的轴向和径向的分布。     

Pyrometer unit for GaAs substrate temperature control in an MBE system

An optical pyrometer designed for precision measurement of the GaAs substrate temperature during MBE growth is considered. The pyrometer can be calibrated against a certain characteristic absolute temperature that is visually determined from a change in the RHEED pattern. This enables one to calculate the absolute temperature of the substrate with regard to its radiant emissivity and minimize the inaccuracy of radiation temperature measurement. The inaccuracy is associated with the deposition of growth products on the pyrometer window.     

低温红外辐射源研究

随着空间红外探测、卫星遥感等技术的飞速发展,低温红外辐射源的需求日益迫切。研制了一种基于液体循环控温原理的低温红外辐射源。辐射源的工作温度范围为-60℃～50 ℃,控温精度达到0.01 ℃,有效发射率优于0.999 7。首先阐述了低温红外辐射源的设计原理,介绍了辐射源腔形设计,使用基于蒙特卡罗算法的软件STEEP3计算了辐射腔的有效发射率;接着对辐射腔内部温度特性进行了研究,实验结果表明低温红外辐射源辐射腔温度均匀性优于0.02 ℃,腔底温度稳定性优于0.05 ℃/h;最后通过与镓熔点黑体比较得到低温红外辐射源在29.76 ℃时的光谱发射率,与仿真计算结果一致。     

冲击波加热的氩气的发射光谱

为了研究弱冲击条件下氩气的辐射特性,从二级轻气炮发射的89 W飞片以2.00 km/s的速度撞击封装有常态下氩气的LY12铝靶,用六通道瞬态高温计和示波器记录到受一次冲击压缩的氩气的光辐射信号随时间的变化规律:从405 nm到700 nm的5个通道信号为直线段,800 nm通道的信号为指数曲线段,并测量出相应的冲击波速度为4.10±0.09 k m/s.实验表明,冲击压缩的氩气对可见光的吸收系数较小,气体的光学厚度沿长波方向从光学薄向光学厚转变.二次冲击压缩氩气的辐射信号上升前沿的时间分辨光谱用OMA系统记录,并观察到450 nm附近有较强的发射光谱带,但没有观察到明显的线状光谱.通过冲击波后参数和氩气电离度的理论计算,解释了冲击压缩下氩气的发射光谱特性.     

Slab band absorptance for molecular gas radiation

Nongray molecular gas radiation can be formulated in terms of slab band absorptance, which can be calculated from correlations of laboratory-measured values of band absorption. Slab-band absorptance is not only useful for obtaining the emissivity or mean beam length but also for the formulation of the radiant flux in a nonisothermal gas. Effects of nongray self-absorption by cold boundary layers can then be readily estimated. Illustrative results are presented for gas in a channel with simple straight-line boundary layer profiles at the walls and constant temperature in the center.