国际比对报告

比对范围质量参加比对实验室德国（ＰＴＢ）、法国（ＬＮＥ）、意大利（ＩＭＧＣ）、荷兰（ＮＭＩ）、日本（ＮＲＬＭ）、加拿大（ＮＲＣ）等比对主题高粘滞性粘度标准国际比对以及表面张力校正系数测试组织者欧洲计量标准合作组织比对结果表面张力粘滞测定法国际比对于１...     

量块的国际比对

从１９９６年到１９９８年，中国计量科学研究院（ＮＩＭ）与德国联邦物理技术研究院（ＰＴＢ）进行了一系列的量块双边比对。本文给出了ＮＩＭ此次比对的结果及不确定度的评定，同时给出德方的部分结果。双方的测试结果在不确定度范围内取得了很好的一致。     

新型水三相点瓶与国家基准水三相点瓶的比对

2002年11月由国际计量局组织的水三相点瓶的国际关键比对（简称CCT－K7），中国计量科学研究院研制出新型结构的水三相点瓶，本文详细介绍了新型水三相点瓶，并将其与国家基准水三相点瓶进行了比对，同时，给出了比对结果。     

齿轮螺旋线量值国际比对结果及分析

本文介绍了中国（ＮＩＭ）与德国（ＰＴＢ）关于齿轮螺旋线量值的国际比对情况和结果分析。互相差最大为０．７μｍ，吻合得很好。     

国际计量委员会各咨询委员会关键比对及工作组简介

国际计量委员会各咨询委员会关键比对及工作组简介一、电磁咨询委员会（ＣＣＥＭ）——建于１９２７年主席：Ｅ．Ｏ．Ｇｏｂｅｌ（德国ＰＴＢ）执行秘书：Ｔ．Ｊ．Ｗｉｔ（国际计量局）成员：法国南非澳大利亚丹麦俄罗斯日本意大利韩国新西兰中国美国英国印度加拿大荷兰瑞...     

CCT-K7水三相点容器国际关键比对

在国际互认框架内,国家计量标准的国际等效性是通过国际计量委员会（CIPM）的咨询委员会组织的一系列国际关键比对来确定的。温度咨询委员会（CCT）委托国际计量局（BIPM）作为主导实验室组织了由20个国家实验室参加的CCT-K7水三相点容器国际关键比对。比对结果表明：这些国家基准水三相点值在0．171mK范围内一致。此外,为了减小国家实验室复现水三相点的系统差,需要进一步研究同位素组成对水三相点温度的影响以及同位素修正。     

NIM水三相点瓶的制作

本文介绍了水三相点瓶的制作理论依据及制作过程，此外，将新制作的水三相点瓶与中国计量科学研究院保存最好的国际基准水三相点瓶进行了比对，并给出比对结果。     

中国计量科学研究院与国际计量局约瑟夫森电压基准之间的直接和间接比对

１９９５年１１月３—１０日，中国计量科学研究院（ＮＩＭ）的１Ｖ约瑟夫森结阵电压基准（ＪＪＡＶＳ）与国际计量局（ＢＩＰＭ）的１Ｖ约瑟夫森结阵电压基准之间进行了直接比对．比对在中国计量科学究研院进行，比对结果的综合不确定度为：（－０．０１±０．１１）ｎＶ．实际测量标准电池的比对结果为：（－１．８±５６）ｎＶ．     

国际比对最终报告

比对范围压力比对主题０８ＭＰａ至８ＭＰａ（气体介质、压力计型式）范围压力标准比对参加比对研究院土耳其国家计量研究院（ＵＭＥ）、意大利国家计量研究院（ＩＭＧＣ）组织者双边比对结果土耳其国家计量研究院和意大利国家计量研究院于１９９６年在土耳其进行了以气...     

传递水三相点容器在国际计量局的比对

国际计量局作为主导实验室组织了由20个国家计量标准实验室参加的CCT-K7水三相点容器国际关键比对.按照比对协议,参加者均选择了1个校准的传递容器送到国际计量局与两个共同的参照容器进行比对.介绍了国际计量局的比对,包括:冻制方法、实验装置、测量步骤、比对结果及相应的不确定度评定.比对结果表明:多数水三相点容器在0.15 mK范围内一致.     

Influence of the Freezing and Annealing Conditions on the Realization of Cryogenic Triple Points

As a basis for evaluating the results of an international star comparison of sealed fixed-point cells, dedicated investigations have been directed to the dependence of the melting temperature on different conditions concerning the preparation of the solid phase, i.e., fast and slow freezing, refreezing without supercooling, or annealing at a temperature of only a few mK below the melting temperature. Differences in the typical thermophysical behavior of the four fixed-point substances hydrogen, neon, oxygen, and argon have been found. In the case of hydrogen and oxygen, the quality of the crystal lattice has little influence on the melting temperature. This enables temperature widths of the melting curves of only a few tens of μK, if there are no additional influences. On the contrary, argon samples frozen after supercooling with different velocities of freezing typically melt within a range of 0.3 mK. The melting-curve width can be reduced only by refreezing. A broader melting range of a few tenths of mK has been typically observed for neon cells. Unlike argon, an improvement of the crystal quality by a slow refreezing does not decrease the width of the melting-curve.     

气体微流量测量技术的发展

本文介绍了美国NIST、德国PTB、日本NMIJ、意大利IMGC、韩国KRISS、中国计量科学研究院NIM和国防科技工业真空一级计量站(兰州物理研究所LIP)的气体微流量测量技术的研究进展,并对其测量方法,测量装置性能指标进行了评述。     

Investigation of the Parameters of Sealed Triple-Point Cells for Cryogenic Gases

An overview of the parameters of a large number of sealed triple-point cells for the cryogenic gases hydrogen, oxygen, neon, and argon is given that have been determined within the framework of an international star intercomparison to optimize the measurement of melting curves as well as to establish complete and reliable uncertainty budgets for the realization of temperature fixed points. Special emphasis is given to the question, whether the parameters are primarily influenced by the cell design or the properties of the fixed-point samples. For explaining surprisingly large periods of the thermal recovery after the heat pulses of the intermittent heating through the melting range, a simple model is developed based on a newly defined heat-capacity equivalent, which considers the heat of fusion and a melting-temperature inhomogeneity. The analysis of the recovery using a graded set of exponential functions containing different time constants is also explained in detail.     

Improved Thermal Model for the Realization of the Triple Points of Cryogenic Gases as Temperature Fixed Points

The realization of the triple points of the cryogenic gases hydrogen, neon, oxygen, and argon as temperature fixed points at the highest level of accuracy requires consideration of the special properties of these fixed-point substances, as done in a general measurement protocol published elsewhere. The protocol is applied to the apparatus and methodology used for an international star intercomparison of sealed fixed-point cells. A generalized thermal model is developed to include the coexistence of different solid?Cliquid interfaces and various thermal resistances. This results in further components in the detailed uncertainty budget for the correction of the measuring power of the thermometer and for the extrapolation to the liquidus point. As a basis for an optimum fixed-point realization, especially an explanation is given why extremely long time periods may be necessary for the thermal recovery after pulses of the intermittent heating used for the calorimetric method.     

Cryostat for Fixed-Point Calibration of Capsule-Type SPRTs

A cryostat for fixed-point calibration of capsule-type SPRTs (standard platinum resistance thermometers) was developed. Using this system, cryogenic fixed points defined on the International Temperature Scale of 1990 (ITS-90) were realized. The cryogenic cells were argon, oxygen, neon, and two equilibrium-hydrogen (e-H₂) cells, made by INRiM, Italy. The uncertainty of the realization of each fixed point was estimated to range from 0.53 mK to 0.43 mK (k = 2). The realizations of the triple point of e-H₂ using two sealed cells coincided within 0.1 mK. Therefore, we are able to calibrate capsule-type SPRTs down to 24.5561 K within an uncertainty of 1 mK (k = 2) by this system. A closed-cycle helium gas refrigerator was used for the cryostat. Each sealed cell was designed so that it could accommodate three sealed cells in the thermometer wells made within the cell. Therefore, the cryostat was designed to accommodate only one sealed cell at a time. The base temperature of this liquid-free cryostat, when one sealed cell and three capsule-type SPRTs were attached for calibration, was ~17 K. For the realization of the triple point of e-H₂, we used liquid helium for additional cooling. Adiabatic melting of the triple point was realized by controlling the inner-most radiation shield at a temperature very close to that of the triple point, and by applying a heat pulse by a heater directly wound to the cell. The amount of the heater power and the waiting time for the thermal equilibrium after each heat pulse were chosen in a way that the adiabatic melting could be finished within ~6 h for each cell. The triple point of each cryogenic fixed point was deduced from the equilibrium temperatures between the heat pulses and subsequent extrapolation to the liquidus point. For the oxygen cell, temperatures of two solid?Csolid transitions (???C?? and ???C?? transitions) were also measured, and the results were consistent with values reported in the literature within the designated uncertainty.     

An Adiabatic Calorimeter for the Realization of the ITS-90 in the Cryogenic Range at the LNE-CNAM

The LNE-CNAM, in cooperation with the IPN, has recently developed a new cryogen-free adiabatic calorimeter, to realize the International Temperature Scale of 1990 (ITS-90) in the temperature range between 6 K and 84 K. The new calorimeter, cooled by a closed-cycle Gifford-McMahon refrigerator, is equipped with three thermal shields and two separate vacuum chambers, to minimize the effect of parasitic heat fluxes. The inner adiabatic chamber can accommodate either a multi-compartment cell??containing the triple points of hydrogen, neon, oxygen, and argon, to realize the ITS-90 between 14 K and 84 K??or a comparison block for thermometers, the calibration of rhodium?Ciron (RhFe) thermometers between 6 K and 24 K. The use of a cryogen-free system and a fully computer-controlled measurement chain allow long lasting experiments and good thermal control, resulting in a substantial reduction of the measurement uncertainties. The new adiabatic calorimeter has been successfully tested at the LNE-CNAM. The overall standard uncertainties in the realization of the ITS-90 have been reduced from 2.08 mK to 0.37 mK at the hydrogen triple point, from 1.40 mK to 0.30 mK at the triple point of neon, and are maintained below 0.26 mK at the triple points of oxygen and argon. In the temperature range between 6 K and 24 K, calibrations of rhodium?Ciron resistance thermometers have been carried out with a standard uncertainty of the order of 0.80 mK.     

准绝热密封氩三相点复现装置

氩三相点作为国际温标ITS-90的重要低温固定点,在国家基准量值传递中有着重要的意义。中国计量科学研究院研制了基于准绝热原理的密封型氩三相点装置,能够对长杆铂电阻温度计进行氩三相点高精度复现,并且通过开发自动控制与测量软件实现了实验过程自动化测量与控制。实验结果表明,使用新研制的密封氩三相点装置使氩三相点的温坪时间提高到23 h以上,其中在16 h的温坪变化在0.2 mK以内,同时温坪复现性达到0.1 mK以内,成功解决了恒定热流法氩三相点复现过程中温坪时间短、复现难度大等问题,保证国家基准量值传递的准确性。     

Realization of the ITS-90 at IMGC in the range of long stem PRTS

IMGC has established the fixed points required by the International Temperature Scale of 1990 (ITS-90) for long-stem platinum resistance thermometers (PRTs) at the highest accuracy level. The present paper describes the fixed point apparatus and the measuring procedures used at IMGC for the accurate realization of each fixed point, and gives some data on the typical phase transitions thereby obtained. Moreover, since IMGC has developed both traditional and sealed cells for the realization of the freesing or melting points of metals, the different types of cells and the procedure used for their construction and preparation are also supplied. Finally, the reproducibilities of the freezing points of Sn, Zn, Al, and Ag were evaluated by means of several determinatiaons with one standard thermometer.Translated from Izmeritel'naya Tekhnika, No. 12, 58–62, December, 1993.     

Isotopic Effects on the Temperature of the Triple Point of Water

An investigation into the effects of isotopic composition on the triple point temperature of water has been carried out at the National Institute of Metrology (NIM), China, since redefinition of the kelvin with respect to Vienna Standard Mean Ocean Water (V-SMOW) was officially proposed by the Consultative Committee for Thermometry (CCT) in 2005. In this paper, a comparison of four cells with isotopic analyses and relevant results corrected for isotopic composition, employing the isotope correction algorithm recommended by the CCT, is described. The results indicate that, after application of the corrections, the maximum temperature difference between the cells drops from 0.10 mK to 0.02 mK and that these cells are in good agreement within 0.02 mK. Also, temperature deviations arising from isotopic variations fall in the range from −55.9 μK to + 40.7 μK. We consider that the distillation temperature and degassing time of the production procedure lead to isotopic variations.     

Intercomparison of gas flow-rate measurements at IMGC, Italy, and UASG, Germany, in the range from 10 to 10 Pa m/s

Primary standard gas flow meters are developed for various applications such as calibration of leak artefacts, generation of calibration pressures by dynamic gas expansion and calibration of secondary standard gas flow meters. The Istituto di Metrologia “G. Colonnetti” (IMGC), Italy, and the University of Applied Sciences Giessen-Friedberg (UASG), Germany, maintain primary flow meters based on different principles in order to measure small gas flows delivered either to vacuum (i.e. practically zero pressure) or to atmosphere (ambient pressure). The principle, design and properties of these flow meters are described. Comparison of the primary standard flow meters maintained at these laboratories was performed over a range from 3×10⁻⁸ to 7×10⁻⁴ Pa m³/s with nitrogen, using a crimped capillary leak as a transfer standard. IMGC was the pilot laboratory. During the intercomparison, the transfer standard changed by ca. −2% for flow to vacuum and by ca. −4% for flow to atmosphere without obvious reason. The results of the intercomparison show that the laboratories agree within their expanded uncertainties over the measured range of gas flows.