Photon stimulated desorption from copper and aluminum chambers

Photon stimulated desorption from aluminum and electroplated vacuum chambers have been obtained using synchrotron radiation of critical energies ranging from 12.4to280eV. The authors first compared different cleaning methods on electroplated copper, including bakeout, prebakeout (bakeout in situ, venting, and pumping) and glow discharge with argon and 10% oxygen. As expected in situ bakeout gave the best results, followed by glow discharge, which was quite effective in removing desorbed gases. After this experiment, the authors compared two different copper electroplating methods, Fluhmann and CERN workshop electroplated copper, giving results with factors from 1 to 3 for initial yields. During dose accumulation, the cleaning effect was more clearly seen in CERN plated copper than in Fluhmann plated copper, specially for hydrogen. After this dose accumulation and with no beam circulating, gas desorption yields were found to decrease quickly except that of water, which decreased slowly, suggesting a proces...