Pumping speed of a high vacuum sorption pump: determination of condensation coefficients

✍ Scribed by C.V.G. Nair; P Vijendran

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 394 KB
• Volume: 27
• Category: Article
• ISSN: 0042-207X
• DOI: 10.1016/s0042-207x(77)80423-5

✦ Synopsis

A high vacuum sorption pump with a speed of 14 I/sec for air has been developed and its various characteristics are given. A final pressure of 2 x 10-7 torr was achieved by this pump in a two-stage pumping of air from 760 torr. The pumping speeds for various gases were investigated in the pressure range from 10 -6 to 10 -3 torr. The condensation coefficients for these gases were evaluated from the respective pumping speeds and found to be 3.5 x 10-3, 3.9 x 10-3, 4.8 x 10-3, 2.1 x 10-3 and 0.4 for air, N2, 02, Ar and C02, respectively. These results have been compared with the existing data. A dependence of the condensation coefficient on the gas pressure as well as on the quantity of the pumped gas was observed. The ultimate pressure attained significantly depended on the quantity of the pre-adsorbed gas.