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TY - CONF AU - Perez Rodriguez, A. AU - Ferreira, L.M.A. AU - Sublet, A. ED - Schaa, Volker RW ED - He, Yuan ED - Li, Lu ED - Zhao, Ning TI - SUBU Characterisation: Bath Fluid Dynamics vs Etching Rate J2 - Proc. of SRF2017, Lanzhou, China, July 17-21, 2017 C1 - Lanzhou, China T2 - International Conference on RF Superconductivity T3 - 18 LA - english AB - The chemical polishing bath SUBU is widely used at CERN to prepare copper RF cavities surfaces before niobium thin film coating; examples are HIE-ISOLDE, LHC and future FCC accelerating cavities. The performance of the polishing process is affected by bath temperature and fluid dynamics. As part of on-going activities to characterise SUBU, the actual study was done to identify a correlation between the etching rate and physical parameters linked to the bath fluid dynamics. A first approach was made using experimental data from a simplified model setup, transposing them via numerical simulation to a real cavity geometry and verifying the agreement with an experiment in a real size (HIE-ISOLDE) mock-up. In a second approach to improve the accuracy of the calculation, the relation of the measured local etching rates, extracted from the mock-up, to flow dynamics quantities extracted from simulation was investigated. As a result, a correlation between the local etching rate and the turbulence kinetic energy was obtained. This correlation can be exploited to improve the polishing tools and so optimise the current process, as well as to predict the etching rate in other cavity geometries. PB - JACoW CP - Geneva, Switzerland SP - 575 EP - 579 KW - ion KW - cavity KW - simulation KW - ISOL KW - software DA - 2018/01 PY - 2018 SN - 978-3-95450-191-5 DO - 10.18429/JACoW-SRF2017-TUPB078 UR - http://jacow.org/srf2017/papers/tupb078.pdf ER -