Accession Number : AD0285476

Title :   CRYOPUMPING IN THE NEAR FREE-MOLECULE FLOW REGION

Corporate Author : ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AIR FORCE STATION TENN

Personal Author(s) : WANG,E.S.J. ; COLLINS,J.A. JR. ; HAYGOOD,J.D.

Report Date : OCT 1962

Pagination or Media Count : 1

Abstract : Results are presented of an experimental study on the cryopumping of CO2 at liquid N2 temperature at pressures where the mean free path is comparable to the cryosurfac dimensions. In this range, it is shown that the pumping speed is no longer constant as it is in the low pressure ranges (free-molecule flow), but increases with increasing pressure through what is termed the tr nsitio region and approaches a constant value in the higher pressure ranges (continuum flow). The pumping speed in the continuum region is shown to be as much as three times that in the free-molecule region. Theoretical analyses of experimental results are presented, including an explanation of the threefold increase in pumping speed. (Author)

Descriptors :   *CARBON DIOXIDE, *CRYOGENICS, ANALYSIS, LIQUEFIED GASES, LOW TEMPERATURE RESEARCH, NITROGEN, PRESSURE, RAREFIED GAS DYNAMICS, TESTS, THEORY, VACUUM APPARATUS

Distribution Statement : APPROVED FOR PUBLIC RELEASE