A-30 degrees C to 80 degrees C Stirred-Liquid-Bath-Based Blackbody Source

摘要

At the national facility for blackbody source radiance temperature calibration of the National Institute of Metrology, China, a stirred liquid bath blackbody was developed for use as a radiance temperature reference source, which has a temperature range from to -30 degrees C to 80 degrees C. This blackbody source consists of a stirred liquid bath, a blackbody cavity, a standard capsule platinum resistance thermometer, and a dry-air purging system. The cavity is cylindrical with 31 degrees V grooves on the inner wall. The cavity is 80 mm in diameter, with a depth of 520 mm, and is immersed in a bath filled with a water-ethylene glycol mixture. The average normal emissivity of the cavity is calculated to be better than 0.9999 with V grooves and when painted with Nextel 811-21 coating. The temperature stability of the blackbody source is 0.005 degrees C over a period of 20 min, and the temperature uniformity of the cavity bottom is 0.02 degrees C. The standard uncertainty of the radiance temperature of the stirred liquid bath blackbody source is estimated to be 0.013 degrees C.