Accession Number : AD0820430

Title :   MEASUREMENT OF EMITTANCE OF TRANSPARENT MATERIALS AT LOW TEMPERATURE.

Descriptive Note : Summary technical rept. 28 Feb 66-28 Feb 67,

Corporate Author : NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA

Personal Author(s) : Schleiger, Eugene R. ; Webb, Lyman A.

Report Date : JUL 1967

Pagination or Media Count : 40

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.

Descriptors :   (*THERMOCOUPLES, CALIBRATION), (*TRANSPARENT PANELS, EMISSIVITY), (*WINDSHIELDS, MANNED SPACECRAFT), CALORIMETRY, THERMAL RADIATION, SPECIFIC HEAT, INFRARED FILTERS, CRYOGENICS, SPACECRAFT CABINS, TEMPERATURE CONTROL, LOW TEMPERATURE.

Subject Categories : Thermodynamics
      Manned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE