CONSIDERATIONS IN THE MEASUREMENTS OF CRYOPUMPING CAPTURE COEFFICIENTS
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN
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A survey is presented of the more important practical and theoretical relationships involved in the study of cryopumping. Starting with a rigorous definition of the capture coefficient, the effects of temperature on the measured values are derived. Several practical points in the design of a chamber for cryopumping measurements are given, including cryosurface and gage placement, calibration, effects of outgassing and impurities, and temperature measurements.