AVS 49th International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeM

Paper VT-WeM3
Comparison of Outgassing Rates of Bare and TiN-coated Stainless Steel Vacuum Chambers*

Wednesday, November 6, 2002, 9:00 am, Room C-104

Session: Outgassing
Presenter: R. Todd, Brookhaven National Laboratory
Authors: P. He, Brookhaven National Laboratory
H.C. Hseuh, Brookhaven National Laboratory
M. Mapes, Brookhaven National Laboratory
R. Todd, Brookhaven National Laboratory
D. Weiss, Brookhaven National Laboratory
D. Wilson, Brookhaven National Laboratory
Correspondent: Click to Email
The stainless steel vacuum chambers of the 248m accumulator ring of Spallation Neutron Source (SNS) are to be coated with ~ 100 nm of TiN to reduce the secondary electron yield. Each SNS chamber is approximately 4m long and over 20cm in diameter. The coating is produced by DC magnetron sputtering using a long cathode imbedded with permanent magnets. Reports in literature suggest that the potential benefit of a TiN coating as a hydrogen permeation barrier that reduces the ultimate outgassing rate. The outgassing rates of several SNS chambers were measured with and without TiN coating of various thicknesses, and before and after in-situ bake. No improvements in outgassing were observed with the coated chambers. The results of the coated chambers were compared with the surface structure and thickness of the TiN coatings as analyzed using AES and SEM. A correlation between film density and outgassing rate was found. *Work performed under the auspices of the U.S. Department of Energy.