Abstract
Outgassing rates from a turbomolecular drag pump (TDP) are measured and compared with those from a turbomolecular pump with axial stages only (TAP). Before baking, outgassing rates of both types of TMPs fit the same time-dependent curve. After baking, on the other hand, outgassing rates of the TDP are 1/3 to 2/3 of those of the TAP. The structure, material, surface finish, and contamination might affect the outgassing rates. So, the current results show that we can evaluate quantitatively the effect of these factors on pumping performance using outgassing rates.
