Spaceborne radiance temperature standard blackbody for Chinese high-precision infrared spectrometer

Abstract

As a radiance temperature standard source for the Chinese high-resolution spectrum infrared spectrometer, the National Institute of Metrology, China, developed a spaceborne radiance temperature standard blackbody (SRTSB) combined with a series of miniature phase change fixed points (MPCFPs) for temperature calibration and emissivity verification using a thermal radiation loop (TRL). The MPCFPs of the SRTSB contain H2O, Ga, Ga–Sn alloy, and phenyl salicylate. The TRL is used to measure the emissivity of the spaceborne blackbody on the basis of controlling environmental radiation. Experimental results show that the blackbody emissivity is higher than 0.998 and the temperature control stability is better than 5 mK. Temperature control uniformity at the cavity bottom and axial are better than or equal to 11 mK and 38 mK, respectively, in the working temperature range of 268.15 K to 331.15 K.. The repeatability of the MPCFPs is less than 5 mK, and the results of the continuous phase transition of the MPCFPs are in a clear temperature plateau. The expanded uncertainty of the SRTSB is lower than or equal to 0.084 K (k = 2).

Effect of cosmic rays irradiation on the phase change characteristics of an on-orbit fixed point

“…Experiments were conducted on the International Space Station with the ITS-90 standard material Ga, and it was found that within a few mK of uncertainty, no significant difference was observed between the melt temperature of the Ga at 1 g and in microgravity. Hao Xiaopeng et al [11,12] studied the fixed point phase change plateau of Ga and Ga-In alloys and showed that the melting point temperature of the Ga and Ga-In alloy fixed point had a good linear relationship with the heating power. Additionally, the phase-change temperature plateaus of six types of miniature fixed points, namely, H2O, Ga-Sn, Ga-Zn, PS, succinonitrile, and Ga, were tested.…”