Improvements of Measuring the Hemispherical Emittance of Selective Coating for All-Glass Evacuated Collector Tubes

The hemispherical emittance of the selective coating in all-glass evacuated tubes should be no larger than 0.080 at 80°C± 5°C in “All-glass evacuated collector tubes” of China national standard. A novel equipment to determine the hemispherical emittance of the selective coating in the normal evacuated tubes was designed and set up. Some of hemispherical emittances of Al-N/Al absorbing coatings in all-glass evacuated tubes were measured.