INITIAL STUDY OF THE EFFECT OF CRYOSURFACE GEOMETRY ON CRYOPUMPING
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFS TN
Pagination or Media Count:
An experimental study of cryogenic pumping using several cryosurfaces in the pressure ranges of .0001 and .001 mm Hg is presented. At these pressures, where the mean free path of the condensable gas is on the order of the cryosurface dimensions, it is shown that the pumping rate is no longer a constant as it is in free-molecular flow, but increases through what is termed the transition range and presumably approaches a higher constant value in the continuum flow regime. Flow in the gas kinetic, gas dynamic, and transition regimes is discussed. Experimental results are presented showing the effects on cryopumping of the addition of fins or ribs to a cryosurface, and the effect of pumping with parallel cryosurfaces at different separations.