Main text This report outlines the equipment, measurement method, results and uncertainties associated with the participant measurements for the Consultative Committee of Thermometry Key Comparison K10 (CCT-K10), "ITS-90 realisations above the silver point using two transfer radiation thermometers and a set of high temperature fixed-point blackbody cells", over the period from around summer 2014 to the final measurements made during January 2020. The report presents differences of the participant data from the KCRV values for both the radiation thermometer and HTFP measurements. Note: this interim report excludes the measurement data of VNIIM, Russia - see explanation at the end of Section 6. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Core body temperature measurement is a key indicator of human health. However, its measurement, although very widely performed, is also often unreliable, especially through infra-red methods. This unreliability can lead to incorrect clinical diagnoses, treatment pathways and decisions about infection status, as, for example, during the recent Covid-19 pandemic. Here we give an outline of the issue and describe work undertaken by the CCT Task Group for Body Temperature Measurement to improve this situation. This has been through initiating a key comparison of body temperature calibrators, developing best practice for body temperature measurement by ear and forehead thermometers and thermal imaging and increasing engagement between metrology and clinical thermometer standards communities.

Aluminum-based eutectic alloys exhibit melting and freezing plateaus analogous to the metal-carbon eutectic fixed point. To economically investigate the behavior of the eutectic cells, a special graphite crucible with stainless-steel enclosure was designed. The plateau temperature of eutectic alloys with precise ratios of Al combined with 70% silver (Ag), 33%copper (Cu), or 95%zinc (Zn) was assessed similar to high-temperature fixed points. Melting and freezing curves for Al(660.323 degrees C), Al-Ag(568 degrees C), Al-Cu(548 degrees C), and Al- Zn(381 degrees C) cells, when heated in a portable drybody thermostat, were determined using a standard type-S thermocouple. Results indicated a noticeable discrepancy between the melting and freezing temperatures due to the thermal conduction; the thermocouple immersion in the thermostat was not sufficiently deep. By extrapolating the furnace temperature offset to 0 degrees C, the discrepancies were reduced to 77, 150, 141, and 80 mK for Al, Al-Ag, Al-Cu, and Al-Zn cells, respectively. This research suggests that the Al-based eutectic fixed point holds potential for calibrating resistors, thermocouples, and radiation thermometers in future applications.

With the efficient use of energy, the study of emissivity is considered to be of great importance. In industrial production, temperature measurement technology, and many other fields, emissivity research is performed an important role. The emissivity is considered to be an important quantitative parameter for the infrared radiation characteristics of high-temperature coatings. Although the experimental measurement technique for high-temperature infrared spectral emissivity by the integrated blackbody method has been studied, little research has been reported on the integrated blackbody temperature field measurement and the simulation study of the emissivity of the integrated blackbody cavity. Therefore, in this paper, the temperature distribution of integrated blackbody cavity with the graphite cavity bottom is measured at 800°C, 1000°C. Besides, the above results are adopted, and the effective emissivity of the integrated blackbody is numerically simulated, based on the measurement results and the Monte-Carlo ray-tracing method. Thus, the feasibility of integrating the blackbody is demonstrated, the infrared radiation properties of integrated blackbodies are also studied as influenced by the temperature of the blackbody cavity.

The radiometry hybrid method, by introducing a lens to the irradiance method with a 900 nm filter radiometer, was adopted to measure the thermodynamic temperature of the aluminum-copper (Al–Cu) eutectic point, aluminum (Al) freezing point, silver (Ag) freezing point, copper (Cu) freezing point and cobalt carbon (Co–C) eutectic point at the National Institute of Metrology, China. By scanning the uniformity of fixed-point blackbodies, the effective diameters were accurately estimated according to the size of the source effect (SSE). The lens transmittance measurement with the closest diameter aperture was adjusted to reduce the uncertainty of SSE. The discrepancy between the thermodynamic temperature and ITS-90 values (T-T 90) of Al–Cu, Al, Ag, Cu and Co–C fixed point blackbodies were concluded as 0.022 °C, 0.014 °C, 0.097 °C, 0.137 °C and 0.317 °C, respectively. The standard uncertainty of the fixed point thermodynamic temperature was estimated to be (0.1 to 0.3) °C (k = 2).

针对90国际温标(ITS90)中锌固定点(419.53℃)与铝固定点(660.32℃)之间温度间隔过大的问题,研制了 Al-Cu固定点(Cu33wt％,548.16℃)作为辅助固定点.通过自主研发的辐射温度计RT9032来测试Al-Cu固定点的熔化和凝固温度值.对于Al-Cu固定点温度值的选取采取熔化平台的平均值、拐点(Point of Inflection,POI)、上限温度点(Upper Limit,UL)三种方式.研究结果表明:不同的选取方式对于熔化温度并没有产生明显的差异,最大相差34mK,且Al-Cu固定点的重复性均在18mK以内,因此,Al-Cu固定点(熔点)可以作为ITS-90固定点以外的辅助固定点使用.

The active dual-laser temperature measurement method has the advantages of no contact with the target surface, no need to know the emissivity information of the target to be measured in advance and strong anti-interference ability. In the active dual laser temperature measurement model, the effective wavelength value of the detector has a direct influence on the measurement results. However, the influence of detector effective wavelength on the measurement results is still not fully understood. Therefore, in this paper, the effective wavelength of the detector is introduced into the active dual-laser temperature measurement model, the migration rule of the measurement results when the response curve bandwidth changes and response curve moves is studied, and the actual measurement results are analyzed.

基于中国计量科学研究院的高温黑体炉设计了一种适用于钨铼偶等高温热电偶的校准方法.优化设计的均温块测温孔轴向均匀性20 mm范围内小于0.5℃,优选的测温孔与中心孔的辐射温度差异可达到小于0.5℃.经铂铑10-铂热电偶验证了基于高温黑体炉的校准方法,在800～1300℃与S型热电偶标准热电势间差异小于0.5℃,不确定度评估为0.8～1.5℃,k =2.在800～1900℃范围内,测试了多只不同来源的C型钨铼偶热电势并考核了偶丝校准前后的均匀性,实验结果表明,钨铼偶丝与国际标准钨铼偶热电势的差异基本保持在1％以内,校准不确定度为3.7～13.0℃,相对不确定度为0.7％t(t为温度),k=2.

We report new developments in instrumentation and techniques for both acoustic (speed of sound) and radiometric primary thermometry methods. These include both new cylindrical resonators for extending acoustic gas thermometry to higher temperatures and absolute radiation thermometers incorporating InGaAs detectors to extend primary radiometry to lower temperatures than can be achieved using Si-detector based instruments. These new approaches have been established in order to determine the difference between thermodynamic temperature, T, and the International Temperature Scale of 1990 (the ITS-90), T 90, over the temperature range from 430 K to 1358 K as part of the three-year EMPIR project ‘Implementing the new kelvin 2' (InK2). This paper describes the facilities and measurement methodologies for measuring T—T 90 at each of the different institutes, along with an assessment of the target uncertainties. The work is ongoing, but we anticipate that the results of these measurements will ultimately be pooled to provide consensus values of T—T 90 with associated estimated uncertainties. These consensus values will initially feed into the technical annex of the mise en pratique for the definition of the kelvin (MeP-K-19) and, if required, will be used to help to provide a foundation for any future temperature scale.

报告了中国计量科学研究院在参与高温固定点热力学温度国际联合研究后对Pd-C和Ru-C两个新高温固定点的研究成果,为Pd-C(1492℃)和Ru-C(1953℃)设计了两种类型坩埚,可用于校准辐射温度计和高温热电偶.Pd-C和Ru-C的国际温标值(T90)是由固定点-基准高温计外推测量,热力学温度(T)则利用精密光电高温计LP4测量获得,其中LP4经过带有热力学温度值的Co-C(1 324℃)、Pt-C(1 738℃)和Re-C(2474℃)内插分度.实验结果表明:Pd-C和Ru-C的T与T90之间的差值分别为0.25 K和0.29 K;Pd-C的T和T90的不确定度分别为0.32 K和0.45 K,Ru-C分别为0.49 K和0.50 K.研究成果不仅为高温固定点的校准推广应用,也为传递热力学温度建立了重要基础.

中国计量科学研究院自行研制的开口镓熔点装置实现了对镓熔点冻制及复现的自动化,建立了开口镓熔点配置标准铂电阻温度计组成的基准装置.实验结果显示:镓熔点熔化温坪长达50 h,镓熔点的复现性为0.1 mK,闭口结构与开口结构镓熔点量值差异经过气压修正后由0.13 mK减小至0.06 mK,镓熔点温度-气压线性拟合曲线所得数值与90温标中给出的镓熔点气压修正系数一致.

A theoretical model of the infrared spectral emissivity measurement of materials using the integrated black-body principle was established. The effects of the effective emissivity of the non-isothermal integrated blackbody cavity, the observation coefficient and the temperature drop during the sample material push-out were investigated. The device of the infrared spectral emissivity measurement using the integrated blackbody principle was set up which used a Fourier-Transform infrared spectrometer as the infrared radiation detection instrument. The effective emissivity of the integrated blackbody cavity was simulated using Monte-Carlo ray tracing method and the associated validation experiments were carried out. The effects of non-ideal factors, including the size-of-source effect and linearity of the spectral responsivity, on the infrared spectral emissivity measurement using the integrated blackbody principle were investigated. The experimental measurements of the infrared spectral emissivity of a graphite material were carried out at 1000 degrees C, 1300 degrees C and 1500 degrees C, respectively. The results in this article are in good agreement with the literature data better than 5%, which verifies the feasibility of the emissivity measurement method using the integrated blackbody principle at high temperatures.

单固定点延伸和多固定点内插是光电高温计的两种常用分度方法.针对新研制的0.9 μm光电高温计进行了这两种分度方法的比较研究.在500～1800℃测温范围内,利用高温黑体炉作比较源,在整百度点与标准光电高温计进行量值验证,结果表明这两种分度方法的温度示值一致性优于0.2℃,与标准值的误差最大不超过0.6℃.两种分度方法的不确定度分别评估为0.2～1.3℃和0.2～0.8℃,k=2.相对于必须测量高温计光谱响应度及其响应度非线性的单固定点延伸方法,多固定点内插法简单并易操作,且不确定度可保持较优水平.该方法无论作为光电高温计的出厂分度还是周期示值校准,均可为大多数温度校准实验室提供参考.

The differences, T − T90, between thermodynamic temperature, T, and temperature, T90, on the International Temperature Scale of 1990 (ITS-90) above the Cu fixed-point temperature, 1357.77 K, were investigated using relative primary radiometric thermometry. The Ag and Cu fixed points were used as reference points for temperature realization by the ITS-90 (n = 1) scheme. The values of T − T90 for the Ag and Cu fixed points have been previously determined as 46.2 mK and 52.1 mK, respectively. Extrapolating these differences based on the sensitivity coefficient used to propagate the uncertainty in the fixed-point temperature to other temperatures results in values of T − T90 of 325 mK or 303 mK at 3000 °C when using the Ag or Cu point T − T90 difference, respectively. These values were confirmed by realizing n = 1 temperature scales using either the thermodynamic values or the ITS-90 values of these fixed points as the reference temperatures and comparing the differences on the two scales. Measurements at the Co–C eutectic point indicated the consistency of thermodynamic temperature realization using the n = 1 scheme, and also demonstrated the equivalence of absolute and relative radiometric thermometry.

针对光电高温计中光电探测器检测到的电流为10-12～10-5 A,易被噪声淹没,且不利于后续电测仪表的读取,因此设计了一个可变增益的微电流放大器实现不同量程的微电流放大.其电路包含放大电路模块、量程选择模块、数字与模拟模块、电源模块的设计.以ADA4530-1作为放大芯片,采用反馈运算的方法实现pA级的输入电流值的放大和电流-电压的转换,放大倍数为105～109,具有稳定性好、体积小、输入噪声低、偏置电流小等特点.将其应用在温度测量系统中,通过Sakuma-Hattori方程可得电流值所对应的温度,相关实验显示,使用该微电流放大器的光电高温计在600～2200℃的测温范围内不确定度为0.4～1.7℃,已接近国际最高水平.

The Co-C eutectic fixed point has been popular for thermocouple calibration since 2010. In this study, the ITS-90 temperature of a Co-C eutectic fixed-point cell intended for thermocouple calibration of noble thermocouples was measured using a radiation thermometer and a group of Pt/Pd and PtRh10%-Pt thermocouples. Satisfactory consistency was observed for measurements using both methods.

In infrared radiation temperature measurements of wide-dynamic, high-resolution and wide-spectrum, Fourier Transform infrared ( FTIR ) spectrometer is a commonly used measurement unit. The nonlinearity of the spectral responsivity is one of the main uncertainty contributions to wide dynamic infrared spectrum measurements of radiation sources. Based on the flux superposition principle, nonlinearity measurement system of FTIR spectrometer measurement system was established. The experimental research on the drift characteristics of the blackbody radiation source and FTIR spectrometer measurement system during the representative nonlinearity measurement time were carried out. The quasi-linear drift effects on the nonlinearity measurement were eliminated by permuting the aperture measurement order. The nonlinear characteristics of FTIR spectrometer measurement system were experimentally measured at 200 similar to 1 000 degrees C. The nonlinearity measurement results and associated uncertainties at 3. 9 mu m and 10. 6 mu m are reported respectively.

Low size-of-source effect (SSE) infrared optical system design and experimental validation are critically involved. SSE is commonly explored in infrared radiation measurements. The main causes of SSE are the diffraction of the field aperture, the reflection of optical components and objective aberrations. The optical path design and the internal components scattering have an important influence on SSE. Reflective optical system is commonly used in infrared radiation measurements with high temperature region and wide wavelength range, which can eliminate chromatic aberration and reduce coma. A reflective infrared optical system is designed and built based on the high-temperature Fourier transform infrared (FTIR) spectrometer infrared radiation measurement facility at NIM. The ambient scattered radiation and the thermal effect of optical components are controlled via the water-cooled scattered radiation shielding bin and limitation apertures. Experimental validation of the SSE characteristics of the FTIR infrared optical system is carried out via the uniform blackbody radiation source at 500 °C and various sized apertures using the direct measurement method. The corresponding calculation model will be described in the paper. SSE on 3.9 μm is measured via the direct measurement method by using a standard reference blackbody with good temperature uniformity as the radiation source. The effect of reflection is reduced via the high emissivity coating on the apertures. The results show that the effect of the SSE on the FTIR measurement facility at the wavelength of 3.9 μm is less than 2×10-4. Details and results of the infrared optical system SSE measurement will be reported in the paper. All measurements can be traceable to the National Standards of P. R. China.

A high-temperature tungsten-rhenium (W-Re) thermocouple is commonly used at temperatures up to 2000 degrees C for the high melting temperature of the thermoelement materials. When exposed to high temperatures, a thermocouple can show significant thermoelectric drift, which increases measurement uncertainty. The uncontrolled drift may come from the change in the crystallographic structure, oxidization of the thermoelement materials, interaction between the thermoelement materials and insulator materials and some other unknown reasons. Therefore, periodic recalibration of the thermocouple should be performed; however, sometimes it is not possible to remove the sensor out of the process, especially in some special fields, such as a nuclear power plant. Self-validation methods for thermocouples provide a solution to avoid this drawback. In this paper, miniature eutectic fixed-point cells are presented for self-validation of W-Re thermocouples. To prevent the breakage of the graphite crucible, these cylindrical miniature fixed-point cells contain several small independent crucibles and one thermocouple well, which increase the robustness of the miniature cell. The melting temperature was assigned by a radiation thermometer traced to the primary radiation standard at NIM. The effect of the temperature offset and temperature ramping rate on the melting temperature were checked. The performance of the miniature fixed-point cells and type C thermocouple, including characterization of the stability and repeatability, is presented.

In the paper, an in-house W/Re thermocouple was calibrated at the eutectic fixed points of Pd-C (1492 degrees C), Pt-C (1738 degrees C) and Ru-C (1953 degrees C). To correct the temperature error caused by the thermal conduction of the thermocouple sheath, a linear extrapolation method was developed to determine the emf of the thermocouple based on the melting and freezing values at the eutectic fixed points realized with different offset furnace temperatures. In a simpler approach, the average of the melting and freezing values was also used. The results showed that the temperatures corresponding to the emfs derived from the linear extrapolation and the average method agreed (1-2) degrees C with the standard reference values of type-C thermocouple in the temperature range studied.