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Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat LoadNASA s Johnson Space Center (JSC) Building 32 houses two large thermal-vacuum chambers (Chamber A and Chamber B). Within these chambers are liquid nitrogen shrouds to provide a thermal environment and helium panels which operate at 20K to provide cryopumping. Some amount of air leakage into the chambers during tests is inevitable. This causes "air fouling" of the helium panel surfaces due to the components of the air that adhere to the panels. The air fouling causes the emittance of the helium panels to increase during tests. The increase in helium panel emittance increases the heat load on the helium refrigerator that supplies the 20K helium for those panels. Planning for thermal-vacuum tests should account for this increase to make sure that the helium refrigerator capacity will not be exceeded over the duration of a test. During a recent test conducted in Chamber B a known-size air leak was introduced to the chamber. Emittance change of the helium panels and the affect on the helium refrigerator was characterized. A description of the test and the results will be presented.
Document ID
20090015870
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Garcia, Sam
(Jacobs Engineering Group, Inc. Houston, TX, United States)
Meagher, Daniel
(Jacobs Engineering Group, Inc. Houston, TX, United States)
Linza, Robert
(Jacobs Engineering Group, Inc. Houston, TX, United States)
Saheli, Fariborz
(Jacobs Engineering Group, Inc. Houston, TX, United States)
Vargas, Gerardo
(GeoControl Systems, Inc. Houston, TX, United States)
Lauterbach, John
(GeoControl Systems, Inc. Houston, TX, United States)
Reis, Carl
(Hamilton Sundstrand Corp. Houston, TX, United States)
Ganni, Venkatarao (Rao)
(Jefferson (Thomas) National Accelerator Facility Newport News, VA, United States)
Homan, Jonathan
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
September 22, 2008
Publication Information
Publication: 25th Space Simulation Conference. Environmental Testing: The Earth-Space Connection
Subject Category
Engineering (General)
Distribution Limits
Public
Copyright
Public Use Permitted.

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