共查询到19条相似文献,搜索用时 187 毫秒
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氩气等单原子气体的折射率,是检验量子力学从头算理论的重要参数。基于圆柱微波谐振法,精确测量了234~303 K、 0~750 kPa范围内氩气的折射率。测量了圆柱腔内不同压力下4种横磁 (TM) 模式的微波谐振频率,对谐振频率进行非理想因素修正后,结合真空下的微波谐振频率获得氩气的折射率。圆柱腔内微波谐振频率测量不确定度为2×10-8,4种模式获得的氩气折射率的相对标准偏差小于1×10-6。通过氩气的折射率计算获得了氩气的第一介电维里系数,与国际上已发表的结果具有良好的一致性。基于建立的实验系统,后续可开展其他气体的折射率测量。 相似文献
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热力学温度研究表明,国际温标ITS-90定义的一系列固定点与真实热力学温度有一定差异。以量子电压标定的噪声温度计为基础,设计了用于铟凝固点测量的温度探测装置,解决了高温复杂环境下电磁干扰的抑制问题。实验采用研制的噪声温度计系统测量了铟凝固点的热力学温度,测量积分时间100h,在20~500kHz的测量带宽内得到的铟凝固点热力学温度为429.7476K,相对不确定度为11.58×10-6,与ITS-90给出的铟凝固点值相差0.9mK。实验结果可以为国际温标的修订提供参考。 相似文献
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热力学温度是客观世界真实的温度,是制定国际温标的基础,目前声学基准测温法是测量中低温区热力学温度不确定度最小的方法,中国计量科学研究院采用圆柱型定程共鸣腔建立了声学温度计,但是圆柱型共鸣腔的热边界层和黏性边界层修正是影响这种测量方法最主要因素之一,而决定边界层修正的参数是理想气体状态下气体工质的输运性质(黏度和导热系数).双毛细管黏度计测量气体介质黏度和导热系数具有很高的准确性,该方法结合了基准毛细管黏度计和量子化“从头算”的优势,可以有效地降低毛细管基准黏度计的测量不确定度与温度的依赖关系.本文介绍了作者在中国计量科学研究院开展的双毛细管黏度计测量氩气输运性质的研究,测量温度范围为240 ~400 K,测量相对标准不确定度为0.083%. 相似文献
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噪声法是目前国际计量界采用的测量热力学温度的3种方法中的一种,目前只有少数几个国家计量实验室建有计量级的噪声温度计.介绍了中国计量科学研究院开展的噪声法测温新研究,及测量镓熔化点热力学温度的工作.新噪声温度计采用了相关法结构,参考点为水三相点.电子测量系统与当前国外计量级噪声温度计的基本一致,但对前置放大器的性能和开关的结构做了改善.采用新研制的噪声温度计测量了镓熔化点的热力学温度,测量积分时间210 h,测量得到的镓熔化点热力学温度302.9176 K,标准合成不确定度8.9 mK.通过分析测量结果值可知,新噪声温度计测量积分时间达到1750 h,可以将标准合成不确定度减小到3 mK. 相似文献
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准确测定热力学温度是制定国际温标的基础,在温度计量研究中具有重要的科学意义.声学共鸣法是当前最有影响的基准热力学测温方法之一,该方法最大测量不确定度来源于实际气体粘性作用所造成的能量耗散效应,故准确地测定实际气体粘度,对声学共鸣法热力学温度计的应用具有关键影响.在120℃以下的实验研究证实,双毛细管粘度计具有最小的气体粘度测量不确定度.在此基础上,设计建立了一套高温双毛细管粘度计,优化了恒温装置结构设计,研究了该恒温器控温方法,使得恒温系统在室温至400℃,5h的温度稳定性达到±3mK,满足双毛细管粘度计测量高温气体粘度实验要求. 相似文献
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We present a method of measuring the refractive index of dry gases absolutely at 632.8 nm wavelength using a Fabry-Perot cavity with an expanded uncertainty of <3×10?? (coverage factor k=2). The main contribution to this uncertainty is how well vacuum-to-atmosphere compression effects (physical length variation) in the cavities can be corrected. This paper describes the technique and reports reference values for the refractive indices of nitrogen and argon gases at 100 kPa and 20 °C with an expanded uncertainty of <9×10?? (coverage factor k=2), with the additional and larger part of this uncertainty coming from the pressure and temperature measurement. 相似文献
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D. C. Ripple G. F. Strouse M. R. Moldover 《International Journal of Thermophysics》2007,28(6):1789-1799
The NIST acoustic thermometer determines the thermodynamic temperature from measurements of ratios of the speed of sound of
argon in a nearly spherical cavity. We report recent results for T − T
90 on 12 isotherms spanning the range 271–552 K. (T is the thermodynamic temperature and T
90 is the temperature on the International Temperature Scale of 1990.) The results are in excellent agreement with recent acoustic
thermometry results reported by Benedetto et al. in the range from 273 to 380 K and with our previously reported results at
303, 430, and 505 K. The combined data sets are sufficiently redundant and sufficiently distributed over the temperature range
to support a re-determination of the reference function for standard platinum resistance thermometers for a future temperature
scale. The isotherms were analyzed using several methods; the T−T
90 results and related uncertainties are insensitive to the method chosen. The thermal expansion of the stainless-steel resonator
was deduced from the frequencies of the microwave resonances of the cavity. To clearly identify two nearly degenerate eigenmodes
in our nearly axially symmetric resonator, two phased coupling probes were used to control the azimuthal angle of the microwave
excitation. 相似文献
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Progress in the development of an apparatus to compare the thermodynamic temperature of a gas with the temperature as determined
by the International Temperature Scale of 1990 (ITS-90) is reported. The apparatus uses the Rayleigh scattering of light from
a gas to provide an intensive measure of gas density, thus avoiding the need for corrections for dead volumes or wall adsorption
required by conventional gas thermometry. A laser beam is shone through gas in two cells that are at the same pressure but
different temperatures, and the measured ratio of the Rayleigh scattering signals from the two cells can be related to the
ratio of the gas density in the cells. From the density ratio, the thermodynamic temperature of one cell can be inferred if
the other cell is held close to the triple point of water. However, the Rayleigh scattering is weak and signals are small,
making measurements with sufficiently small uncertainty extremely challenging. Since previous reports, the apparatus has been
significantly modified, and these changes are described along with indicative results. In this paper, results of measurements
in the range from 211 K to 292 K using both argon and xenon are reported. The results suffer from large systematic errors
due to contamination in one of the measurement cells. Although the results do not provide reliable estimates of T − T
90, they indicate that measurements with uncertainties below 1 mK are feasible. 相似文献
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为了检验对激光干涉仪测量精度有很大影响的空气折射率测量系统的测试性能,提出一种可用于基于Edlén公式的空气折射率测量系统的校准方法,并且设计了专门的校准装置,该装置主要由温度、气压以及湿度测量系统组成。实验证明:取包含因子k=2时,温度在(5~40)℃区间,测量不确定度U优于0.02 ℃;气压在(66~105)kPa区间,U=18 Pa;湿度在(10~90)%RH区间,U=2.0%RH,等效于整个系统对应的空气折射率测量的相对不确定度优于1×10-7 相似文献
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R. Ding M. J. Zhao E. Nerdrum D. Meier 《International Journal of Thermophysics》2011,32(11-12):2252-2260
A triple-point-of-argon system was developed to realize the argon triple-point temperature defined in the International Temperature Scale of 1990 (ITS-90) and to calibrate long-stem standard platinum resistance thermometers (SPRTs). The system structure, the techniques for realization of the triple-point temperature, and the testing results are presented in this paper. In this system, there is a central argon cell that includes four re-entrant wells with an immersion depth of 160?mm which can be used to calibrate four long-stem SPRTs simultaneously. A high-accuracy temperature controller is used to control the realization process of the argon triple-point temperature plateau. The argon triple-point plateau can be easily realized with this system. The influence of different experimental parameters on the triple-point-of-argon plateau was investigated and is discussed. The testing results show that the duration of the plateau can be over 100?h with the temperature change less than 0.05?mK. The temperature homogeneity of the four re-entrant wells was tested. The immersion profile of the system was measured, and the measurement results were compared with the ITS-90 hydrostatic values. The uncertainty analysis shows that the uncertainty of the argon system is 0.25?mK (k = 2). 相似文献
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P. M. C. Rourke 《International Journal of Thermophysics》2017,38(7):107
The implementation of microwave refractive index gas thermometry at the National Research Council between 24.5 K and 84 K is reported. A new gas-handling system for accurate control and measurement of experimental gas pressure has been constructed, and primary thermometry measurements have been taken using a quasi-spherical copper resonator and helium gas at temperatures corresponding to three defining fixed points of the International Temperature Scale of 1990 (ITS-90). These measurements indicate differences between the thermodynamic temperature T and ITS-90 temperature \(T_{90}\) of \(\left( T - T_{90} \right) = -0.60 \pm 0.56\) mK at \(T_{90} = 24.5561\) K, \(\left( T - T_{90} \right) = -2.0 \pm 1.3\) mK at \(T_{90} = 54.3584\) K, and \(\left( T - T_{90} \right) = -4.0 \pm 2.9\) mK at \(T_{90} = 83.8058\) K. The present results at \(T_{90} = 24.5561\) K and \(T_{90} = 83.8058\) K agree with previously reported measurements from other primary thermometry techniques of acoustic gas thermometry and dielectric constant gas thermometry, and the result at \(T_{90} = 54.3584\) K provides new information in a temperature region where there is a gap in other recent data sets. 相似文献
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对高温气冷堆堆芯温度的可靠测量是目前的技术难题之一。传统温度计依靠实验室标定的材料特性与温度的关系进行测温,然而,长期暴露在高温、高辐照环境中,其测温材料的性质会发生改变且得不到及时校准,温度传感器易发生漂移甚至失效。气体声学温度计通过测量单原子气体的声速可以直接获得热力学温度;由于气冷堆内氦气介质相对稳定,利用氦气声速获得温度具有较高的可靠性。针对实用氦气声学温度计开展了初步研究,基于圆柱声学共鸣法设计了实用声学温度计测试系统,采用声波导管声学传感器测量了488K至806K圆柱共鸣腔内氦气的声学共振频率,修正了热边界层和粘性边界层的影响;基于量子力学从头算得到的氦气声学维里状态方程,获得了热力学温度。对氦气共振频率的测量相对标准偏差小于0.07%,温度测量的信噪比可满足需求,声学温度计与热电偶测温结果差异小于1%。研究结果为未来持续开展极端环境下气体声学温度计的应用研究提供了支持。 相似文献
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The constant-volume gas thermometer (CVGT) of the National Metrology Institute of Japan (NMIJ), AIST with 3He as the working gas is used as an interpolating gas thermometer to realize the International Temperature Scale of 1990 (ITS-90)
from 3 K to 24.5561 K and as a relative gas thermometer for thermodynamic temperature measurement calibrated at the triple
point (TP) of Ne. The standard uncertainties of the realization and measurement are estimated to be 0.58 mK and 0.86 mK at
a maximum in the mentioned temperature range, respectively. The maximum difference between both temperatures is about 1 mK.
In the calibration of the CVGT, the TP of equilibrium hydrogen (e-H2) is corrected for isotopic composition as specified in the Technical Annex for the ITS-90. The ambiguity of the TP of Ne
due to the variability in isotopic composition is included in the uncertainty. Although the CVGT was also used in 2004 to
realize the ITS-90, it was modified for the present experiment to reduce some measurement uncertainty components and the working
gas was replaced with a higher-isotopic-purity gas. The results from 2004 were recalculated by correcting for the isotopic
composition of e-H2 and differ insignificantly from the present results, except for a wider scatter. 相似文献