DIFFUSION PUMP BAFFLE STUDY
Abstract
This study was undertaken to develop and test a diffusion pumping station having maximum pumping speed consistent with minimum backstreaming for use on a large space environmental chamber. The complete system includes pump, duct, and baffle. Conductance measurements were made using small-scale model ducts and baffles to determine the most promising configuration for the full- scale system. As a result of this preliminary work, a 52 inch diameter liquid nitrogen cooled baffle was developed which has a transmission probability of 0. 35 while the reducer duct-baffle combination developed retains 50% of the pumping speed above the baffle. Backstreaming measurements ranged from 7.3 x 10 to the -7th power mg/sq cm-min for a short duration test (63 hours) to 7 x 10 to the -8th power mg/sq cm-min for a long duration test (524 hours). Along with the backstreaming measurements, the residual gas composition in the test dome was checked with a mass spectrometer residual gas analyzer. A lesser aspect of this study was to compare the backstreaming rates of two diffusion pump oils above a liquid nitrogen cooled baffle. The baffle was constructed to approximate the full-scale 52 inch baffle.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1964
- Accession Number
- AD0451427
Entities
People
- M. H. Hablanian