Thermodynamic Temperature Measurement Of The Indium Freezing Point With Johnson Noise Thermometry

Based on the noise thermometer calibrated by quantum voltage,the study of the thermodynamic temperature of indium solidification point was carried out by the noise method.The measurement integration time is 100 hours.The thermodynamic temperature of the indium solidification point at 20 kHz to 500 kHz is 429.7476 K,the relative uncertainty is 11.58 ppm,and the difference is 0.9mK with the indium solidification point given by ITS-90.The study on the measurement of the thermodynamic temperature of the indium solidification point based on the quantum voltage calibrated noise thermometer has proved the feasibility of the measurement technology.It lays a foundation for the research and development of the practical noise thermometer and provides the reference data for the revision of the international thermometer.The main research work is as follows:(1)A temperature detection device for indium freezing point measurement is designed.The thermal noise source detector is an important part of the noise thermometer.Its performance and stability in the working environment of the indium solidification point is the key to research work.(2)Solving the problem of electromagnetic interference suppression under high temperature and complex environment.The working environment of the indium solidification point has complex electromagnetic interference,which will cause serious negative influence on the noise thermometer system.It is very important to find the source of the electromagnetic interference and suppress the interference for the measurement accuracy of the whole system.(3)The matching problem between noise source and transmission line is studied,and the connection between noise source and preamplifier is improved,so that the noise source and the transmission line can be better matched.(4)The quantum voltage noise suitable for indium solidification point is synthesized.The thermodynamic temperature of indium solidification point is measured by the noise thermometer system based on quantum voltage calibration,and the error source and uncertainty of the measurement results are analyzed in detail.