MEASUREMENT OF EMITTANCE OF TRANSPARENT MATERIALS AT LOW TEMPERATURE.
Abstract
Improvements of a previously developed transient calorimetric method of measuring total hemispherical emittance transparent materials are described. They consist essentially of a method of calibrating thermocouples when installed in the dewar by comparison with a platinum resistance thermometer and a method of thermal switching by the temporary introduction of helium gas in the evacuated dewar. The results of emittance measurements of several Irtran filters of thickness 1 mm are presented for the temperature range 44 K to 312 K. Irtran 2 emittance increased from 0.4 at 312 K to a maximum of 0.57 at 180 K and then decreased to 0.49 at 75 K. Comparable figures for Irtran 4 were 0.15 at 312 K, 0.45 at 60 K, and 0.43 at 44 K and for Irtran 6 were 0.24 at 312 K, 0.50 at 100 K, and 0.35 at 44 K. Thicker specimens had in general slightly higher emittance values.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1967
- Accession Number
- AD0820430
Entities
People
- Eugene R. Schleiger
- Lyman A. Webb
Organizations
- Naval Radiological Defense Laboratory