Glock, H.-W.; Dürr, V.; Glöckner, F.; Ries, M.; Vélez, A.; Knobloch, J.: Operational Experience with the Improved VSR DEMO Collimating Shielded Bellow in BESSY II. In: Frank Zimmermann ... [Ed.] : IPAC2022 : Proceedings of the 13th International Particle Accelerator Conference, in Bangkok, Thailand, 12–17 June 2022Geneva: JACoW, 2022. - ISBN 978-3-95450-227-1, p. THPOST025/1-4
https://accelconf.web.cern.ch/ipac2022/papers/thpost025.pdf
Open Access Version
Abstract:
The Collimating Shielded Bellow (CSB) is designed to serve both as a flexible beam pipe connection between two adjacent superconducting cavities as foreseen in VSR DEMO and as a synchrotron light collimator to shield the down-stream cavity from synchrotron radiation. A convoluted inner RF shield was applied to prevent fundamental mode heating of the stainless-steel-made bellow in the cryogenic environment, making the such captured inner volume very difficult to access for inspection and cleaning. A first version of the device (CSB1) was successfully tested as part of the beam pipe of the synchrotron light source BESSY II under regular operation for more than a year. It suffered from an unfavourable long outgassing commissioning. Therefore a detachable design, allowing for rigorous inner surface preparation and cleaning, was built and recently installed in BESSY II. CSB version 2 (CSB2) design and experimental outcomes are described in the paper. First results indicated a significantly improved vacuum commissioning performance, which was confirmed later on.