Condensation/adsorption and evacuation of residual gases in the SRF system for the CESR luminosity upgrade

Condensed/adsorbed gases can enhance field emission in superconducting cavities and deteriorate the input coupler performance in a superconducting RF system. It is therefore important to understand condensation/adsorption of residual gases in such a system. In this paper, we present some related results for the first two superconducting cavities installed in the CESR for luminosity upgrade. The total amount of adsorbed gases for different working periods are compared. Gas species are analyzed. A Monte-Carlo computer code is used to simulate the gas condensation/adsorption profile along the waveguide. The warm-up desorption curve is extracted, which might help us to understand the interaction between gas molecules and substrates. The pumping speed of the window pump-out box was evaluated by using the same code and was compared with the speed due to cryo-pumping. New designs of the pump-out box were explored to improve its pumping speed.