Neumann, A.; Echevarria, P.; Goslawski, P.; Ries, M.; Ruprecht, M.; Vélez, A.; Wüstefeld, G.: RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities. In: Stuart Henderson ... [Ed.] : Proceedings of the 6th International Particle Accelerator Conference - Proceedings of IPAC 2015, Richmond, VA, USA. JACoW, 2015. - ISBN 978-3-95450-168-7, p. MOPHA010/1-4
https://jacowfs.jlab.org/conf/proceedings/IPAC2015/papers/mopha010.pdf
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Abstract:
For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring’s RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zerocrossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and lowpower consumption at a loaded Q of 5 × 107. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated.