Abstract：The structure, working principle, performance test results and uncertainty analysis of the vacuum mercury fixed point blackbody radiation source developed by National Institute of Metrology (NIM), China, were introduced. The perfusion metal of the vacuum mercury fixed point blackbody was high purity mercury with a purity of 99.9999%. The opening diameter of the blackbody cavity is 25 mm, the inner diameter of the cavity is 28 mm, the depth is 260 mm, and the surface is coated with high emissivity coating from NEXTEL 811-21. The Monte Carlo calculation method was used to calculate the blackbody emissivity at the wavelength of 8~14μm. The emissivity is higher than 0.9999. In the vacuum environment, the main technical indicators such as the temperature curve and repeatability of the temperature of the mercury fixed point blackbody were tested. The results show that the temperature stability of the vacuum mercury fixed point blackbody is better than 2 mK, and the repeatability is better than 1 mK. The uncertainty source of the vacuum mercury fixed point blackbody is analyzed, the synthetic standard uncertainty is calculated, and the result is better than 16 mK.
2020, Vol. 41 
