高准确度水三相点容器

High Accuracy Triple Point of Water Cells

水三相点的高精度复现及准确测量是保证国际温标ITS-90实施的关键。水三相点容器内高纯水的同位素组成会影响复现的水三相点温度值。为了提高水三相点复现水平,减小氢氧同位素的影响,研制了带有氢氧同位素分析的石英及硼硅玻璃高准确度水三相点容器。为了评价容器的性能,开展了硼硅玻璃和石英水三相点容器的比对。实验结果表明:同位素修正前,石英玻璃和硼硅玻璃水三相点容器复现的水三相点在0.058 mK范围内一致;同位素修正之后,容器之间的差异在0.017 mK范围内一致。采用高准确度水三相点容器复现水三相点的扩展不确定度为0.066 mK(k=2)。

The high-precision realization and accurate measurement of triple point of water(TPW)are the keys to ensure the implementation of the International Temperature Scale of 1990(ITS-90).The isotopic compositions of the high purity water in the TPW cells affect the temperature of TPW.In order to improve the TPW realization and reduce the influence of hydrogen and oxygen isotopes,quartz and borosilicate glass high-accuracy TPW cells with hydrogen and oxygen isotopic analyses were developed.In order to evaluate the performance of the cells,comparisons between the borosilicate glass cells and the quartz cells were carried out.The experimental results show that,before the isotopic corrections,the temperature differences between the quartz and borosilicate glass high-accuracy TPW cells are within 0.058 mK.After application of the corrections,the temperature differences are within 0.017 mK.The expanded uncertainty of the realization of TPW using high-accuracy TPW cells is 0.066 mK(k=2).