Determination of coating emittance at cryogenic temperatures for the James Webb Space Telescope: experimental methods and results

Warren J. Tolson; Chuen T. Or; Stuart D. Glazer; Mark C. Kobel; Edward A. Packard

doi:10.1117/12.624002

25 August 2005 Determination of coating emittance at cryogenic temperatures for the James Webb Space Telescope: experimental methods and results

Warren J. Tolson, Chuen T. Or, Stuart D. Glazer, Mark C. Kobel, Edward A. Packard

Author Affiliations +

Proceedings Volume 5904, Cryogenic Optical Systems and Instruments XI; 59040G (2005) https://doi.org/10.1117/12.624002
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

A cryogenic thermal vacuum testing facility at NASA's Goddard Space Flight Center (GSFC) was developed to determine thermal control coating emittance at cryogenic temperature for the JWST/ISIM project. In order to meet ISIM thermal requirements in design and analysis accurate knowledge of material and optical properties as a function of temperature for the assembly are required. The optical property data currently available in this temperature regime have a relatively large (30-50%) uncertainty associated with the measurements. In an effort to reduce these uncertainties the 'ISIM Thermal Control Coating Cryogenic Emittance Tests' (3 performed to date) were developed utilizing this facility. The objective of these tests was to determine the emittance of candidate thermal control coatings and radiator geometric configurations for the ISIM over the temperature range from 30K to 150K while minimizing associated uncertainty. This paper presents the testing approach, experimental methods, and results for the emittance tests performed in the GSFC cryogenic facility to date. Challenges encountered during this testing effort included quantifying parasitic heat losses/gains to a high degree of accuracy in an effort to minimize associated measurement uncertainty.

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Warren J. Tolson, Chuen T. Or, Stuart D. Glazer, Mark C. Kobel, and Edward A. Packard "Determination of coating emittance at cryogenic temperatures for the James Webb Space Telescope: experimental methods and results", Proc. SPIE 5904, Cryogenic Optical Systems and Instruments XI, 59040G (25 August 2005); https://doi.org/10.1117/12.624002

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