气体折射率基准方法测量热力学温度的探索

Thermodynamic temperature is one of the most important physcial parameters related to energy equilibrium and energy exchange. The International Temperature Scale of 1990 (ITS90) was also based on the thermodynamic temperature measurements. Now the thermodynamic temperature measurement methods lag to modern physics development. These old methods were all very time-consuming and difficult to use for industry. In this proposal, we combined the new results from "ab initio" theory and microwave techniques to develop the Primary Gas Refractive Index Thermometry (PGRIT) for measuring thermodynamic temperature. The PGRIT experimental system was also built based on the two-cylinder microwave resonance method. The electromagnetic field theory was used to describe the distribution of the electric and magnetic fileds, and then to develop the correction theory for the non-ideal factors. The thermodynamic temperatures will also be measured by the new method in the range of 300 K ~400 K. The possibility to realize the thermodynamic temperature scale rapidly and accurately in the range of 4 K~1200 K by the PGRIT method was also disscussed. This project can not only present new method for international temperature community and supply the important thermodynamic temperature data by independent experiment method, but also fix the reliable and accurate problems of temperature measurement in the nantional defense and aerospace fields.

热力学温度是客观世界真实的温度，是制定协议温度标尺（国际温标）基础。本文针对目前热力学温度测量技术相对滞后于物理学的发展、测量周期长和难以实用化的现状，探索建立基于量子物理"从头算"(ab initio)理论和微波谐振的气体折射率基准测温方法，并由此建立以双圆柱微波谐振为基础测量热力学温度的装置。理论上利用电磁场微扰理论建立描述谐振腔中电磁场分布、非理想因素表现特性和修正模型，建立基于深刻物理机制认识和具有广泛适用性的实验方法和测量模型，寻求基础理论和实验研究的创新，进一步在300 K~400 K范围内有针对性地开展实验研究，并且探究这种方法在4 K~1200 K快速准确复现热力学温标的可能性和所需条件，不仅给国际温度计量界提供新的测量方法和独立的数据，为中国在国际温标制定中获得话语权，而且可以解决国防和航天等领域中的温度可靠准确测量问题。

热力学温度是客观世界真实的温度，是制定协议温度标尺（国际温标）基础。本文针对目前热力学温度测量技术相对滞后于物理学的发展、测量周期长和难以实用化的现状，探索建立基于量子物理"从头算"(ab initio)理论和微波谐振的气体折射率基准测温方法，并由此建立以双圆柱微波谐振为基础测量热力学温度的装置。研究内容主要包括以下几个部分：（1）设计了微波谐振腔体，建立了双圆柱微波谐振腔热力学温度测量实验系统。（2）对双圆柱微波谐振腔气体折射率基准温度计的理论进行了详细的分析。（3）采用电磁场一阶微扰理论，对造成谐振频率扰动的非理想因素（趋肤效应、端盖开孔）进行了分析和测量，并给出了相应的修正模型。（4）优化谐振腔设计，发现将探针天线布置在端盖中心可提高信噪比，确定将不锈钢腔镀铜处理为最优方案。（5）设计和研制恒温槽控温系统，使得谐振腔温度波动稳定在±0.3 mK/h的水平，设计了真空配气系统和频率测量系统。（6）采用LabVIEW软件编写了实验中各仪器的自动控制程序，实现了仪器自动化的数据采集与传输。（7）采用ABAQUS有限元软件对圆柱声学共鸣腔进行建模，模拟了其在不同螺栓预紧力下的变形，并对固有频率进行仿真，与实验测量的实际结果进行比较，二者显示具有良好的一致性，为下一步壳体振动修正理论模型的建立以及共鸣腔共振模式的选取打下了基础。（8）在水三相点温度下，测量了不同压力下氦气的折射率，得到了热力学温度合适的压力测量范围。选取TM010和TM011模式测量了306.2603 K下的热力学温度，得到T-T90=（3.03±4.89）mK，并对气体折射率基准温度计的不确定度进行了评估。