CRYOPUMPING IN THE NEAR FREE-MOLECULE FLOW REGION
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1962
- Accession Number
- AD0285476
Entities
People
- E.s.j. Wang
- J.a. Jr. Collins
- J.d. Haygood
Organizations
- Arnold Engineering Development Complex