Sorption Pumping of Residual Gases at Cryogenic Temperatures

  • J. E. A. John
  • W. F. Hardgrove
Part of the Advances in Cryogenic Engineering book series (ACRE, volume 12)


Since the inception of space vacuum simulation, there has been a need to create, at least in a small test volume, the pressure existent in space, 10-12 to 10-16 torr. Although this level of vacuum has been achieved in research-type facilities, requiring extreme care and expense, the conduct of a test in such a system has not become a routine matter. Reserve pumping capacity must be provided at ultrahigh vacuum to handle the out-gassing load of the test article and, hence, to maintain the vacuum level. Cryogenic pumping, which provides large pumping surfaces and high pumping speeds for the condensable gases, has proven to be a successful technique for the evacuation of test chambers. It is generally recognized that a vacuum greater than 10-14 torr can be created in a leak-free vessel having its interior surfaces maintained at 2.5°K. However, the operation and maintenance of surfaces at liquid helium temperatures and lower present many complex engineering problems. Further, a cryogenic surface is able to pump only those gases with a partial pressure in the test chamber greater than the vapor pressure of the gas at the cryosurface temperature. For example, at 10-11 torr, surface temperatures below 3°K are necessary to pump hydrogen.


Heat Load Cryogenic Temperature Test Volume Diffusion Pump Valve Plate 
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Copyright information

© Springer Science+Business Media New York 1967

Authors and Affiliations

  • J. E. A. John
    • 1
  • W. F. Hardgrove
    • 1
  1. 1.Goddard Space Flight CenterGreenbeltUSA

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