AVS 64th International Symposium & Exhibition
    Vacuum Technology Division Tuesday Sessions
       Session VT-TuM

Paper VT-TuM6
Vacuum Performance of Taiwan Photon Source Storage Ring

Tuesday, October 31, 2017, 9:40 am, Room 7 & 8

Session: Large Vacuum Systems
Presenter: Hsin-Pai Hsueh, National Synchrotron Radiation Research Center, Taiwan, Republic of China
Authors: H.P. Hsueh, National Synchrotron Radiation Research Center, Taiwan, Republic of China
G.Y. Hsiung, National Synchrotron Radiation Research Center, Taiwan, Republic of China
J.R. Chen, National Synchrotron Radiation Research Center, Taiwan, Republic of China
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The Taiwan Photon Source storage ring vacuum system has been developed to be pre-baked and installed under vacuum for 14-m arc sections. The straight sections were in-situ baked followed the installation of adjacent arc sections. During first stage commissioning, foreign object was found and the bending vacuum chamber of this particular arc section was replaced without baking (neither pre-baked and installed under vacuum, nor in-situ baking). Subsequently, four more bending chambers in other four different arc sections were replaced without baking either. Since this time saving method is different from our system design philosophy, a detailed pressure and mass spectrum analysis is necessary. From measured data, the photon stimulated desorption is no longer as dominant as we would like it to be as designed. The thermal outgassing is more than 25% of total outgassing at highest current (400mA or above). The total beam dose is almost 1500 Amp-hour. The photon-stimulated-desorption (PSD) pressure over beam current (ΔP/I) is 2.33E-11 Pa/mA. In this presentation, the analysis results will be presented.