Abstract Wear and internal contamination are two of the primary factors that influence reliable, long-life operation of turbo-Brayton cryocoolers. This paper describes tests that have been conducted and methods that have been developed for turbo-Brayton components and systems to assure reliable operation. The turbomachines used in these coolers employ self-acting gas bearings to support the miniature high-speed shafts, thus providing vibration-free operation. Because the bearings are self-acting, rubbing contact occurs during start-up and shutdown of the machines. Bearings and shafts are designed to endure multiple stop/start cycles without producing particles or surface features that would impair the proper operation of the machines. Test results are presented that document extended operating life and start/stop cycling behavior for machines over a range of time and temperature scales. Contaminants such as moisture and other residual gas impurities can be a source of degraded operation if they freeze out in sufficient quantities to block flow passages or if they mechanically affect the operation of the machines. A post-fabrication bakeout procedure has been successfully used to reduce residual internal volatile contamination to acceptable levels in closed-cycle systems. The process was developed during space qualification tests on the Near Infrared Camera/Multi-Object Spectrometer (NICMOS) Cryogenic Cooler (NCC). Moisture levels were sampled over a seven-month time interval following the initial bakeout confirming the effectiveness of the technique. A description of the bakeout procedure is presented.


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    Titel :

    Life and Reliability Characteristics of Turbo-Brayton Coolers


    Beteiligte:
    Breedlove, J. J. (Autor:in) / Zagarola, M. V. (Autor:in) / Nellis, G. F. (Autor:in) / Gibbon, J. A. (Autor:in) / Dolan, F. X. (Autor:in) / Swift, W. L. (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2002-01-01


    Format / Umfang :

    9 pages




    Medientyp :

    Aufsatz/Kapitel (Buch)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch




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