Development Of Blackbody Radiation Source With Vacuum Gallium Fixed Point

The research on vacuum fixed point blackbody is carried out in order to meet the urgent need of the standard of space infrared remote sensing brightness temperature measurement.The national metrological standard traceability system for the traceability of infrared remote sensing load value to meet the requirements of space application environment,the command of the measurement standard which can meet the major aerospace engineering and model in research and future planning,and the target of high quantification of earth observation technology in China,the infrared remote sensing brightness temperature value transfer system was established.With a series of vacuum fixed blackbody radiation sources were used as the maximum measurement standard(the temperature range covering 125K-500 K),the system used the vacuum Fourier spectrometer as the transmission instrument.In this paper,we investigated the theory of the vacuum gallium fixed point blackbody and then created it successfully.The design index of the blackbody is required to be working temperature 29.7646,with the normal effective emissivity 0.9999,the cavity opening 25 mm in diameter,blackbody cavity cone Angle 120 ° and the expanded uncertainty(K=1)is better than that of 30 m K.The design scheme is as follows.1.By using the simulation software STEEP3,which is based on Monte Carlo algorithm,the simulation calculation of the effective emissivity was completed.The results shown that when the blackbody cavity depth of 220 mm,the effective emissivity of blackbody cavity was 0.9999.2.Through thermal analysis and optical analysis,a perfect mechanical design scheme is proposed,which mainly presents the design of temperature control medium cylinder,water bath circulation system and quasi-adiabatic system.3.The mechanical drawing of the blackbody with vacuum gallium fixed point was designed by drawing software.4.After finishing the coating spraying of the vacuum gallium fixation point blackbody cavity,the high-temperature heat treatment of the inner wall of the temperature-controlled medium and the outer wall of the black body cavity(to prevent the contamination of high purity gallium),and the perfusion of high purity gallium(in the sealed environment filled with argon),the vacuum gallium fixation point blackbody was assembled.5.The experimental system of the vacuum gallium fixed point blackbody was established.Based on finite element analysis,using simulation software,the heat transfer performance,uniformity and phase transformation plateau of the vacuum fixed point blackbody were calculated.The simulation results of heat transfer performance are better than 10 m K,the simulation results of uniformity are better than 20 m K,and the simulation results of phase change temperature plateau recurrence are better than 10 m K.The simulation result of normal effective emissivity of blackbody cavity is 0.9999.The performance test of the vacuum gallium fixed point blackbody includes the measurement of the normal effective emissivity of blackbody cavity,the experiment of phase change plateau recurrence and the repeatability of phase change plateau recurrence.In the measurement of effective emissivity of blackbody cavity,two measurement methods are used,one is to measure the emissivity based on the control of environmental radiation change,and the measurement result is 0.9996;the other is to measure the reflectivity by quantum cascade laser,and the measurement result is 0.9996,both of which meet the index requirements.According to the experimental conditions of the blackbody,the phase retrieval results gallium datum point were better than 15 m K.Through the CCTS-WG5 fixed point uncertainty analysis,the uncertainty of the blackbody is better than that of 29 m K,and the phase change plateau emersion repeatability is better than 2.5 m K.