TESTS OF AN ENVIRONMENTAL AND PERSONNEL SAFE CLEANING PROCESS FOR BROOKHAVEN-NATIONAL-LABORATORY ACCELERATOR AND STORAGE-RING COMPONENTS

A large measure of the successful operation of the National Synchrotro n Light Source (NSLS) al Brookhaven National Laboratory (BNL) for over a decade can be attributed to the cleaning of its ultrahigh vacuum (U HV) components during and after construction. A new UHV cleaning proce ss, which has to be environmentally and personnel safe, is needed to r eplace the harsh, unfriendly process which is still in use. Dow Advanc ed Cleaning Systems was contracted to develop a replacement process wi thout the use of harsh chemicals and which must clean vacuum surfaces as well as the existing process. Acceptance of the replacement process was primarily based on photon stimulated desorption (PSD) measurement s of beam tube samples run on NSLS beam line U1OB. One meter long beam tube samples were fabricated from aluminum, 304 stainless steel, and oxygen-free copper. Initially, coupon samples were cleaned and passed preliminary testing for the proposed process. Next, beam tube samples of each material were cleaned, and the PSD measured on beam line U10B using white light with a critical energy of 487 eV. Prior to cleaning, the samples were contaminated with a mixture of cutting oils, lubrica nts, vacuum oils, and vacuum grease. The contaminated samples were the n baked. Samples of each material were also cleaned with the existing process after the same preparation Beam tube samples were exposed to b etween 10(22) and 10(23) photons per meter for a PSD measurement. Deso rption yields for H-2, CO, CO2, CH4, and H2O are reported for both the existing cleaning and for the replacement cleaning process. Prelimina ry data, residual gas scans, and PSD results are given and discussed. The new process is also compared with new cleaning methods developed i n other laboratories. After modification, the new UHV cleaning process was accepted by BNL.