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TY - CONF AU - Qiu, F. AU - Arakawa, D.A. AU - Egi, M. AU - Kako, E. AU - Katagiri, H. AU - Konomi, T. AU - Matsumoto, T. AU - Michizono, S. AU - Miura, T. AU - Sakai, H. AU - Umemori, K. ED - Meseck, Atoosa ED - McAteer, Meghan ED - Schaa, Volker R.W. ED - V\xF6lker, Jens TI - Characterization of Microphonics in the cERL Main Linac Superconducting Cavities J2 - Proc. of ERL2019, Berlin, Germany, 15-20 September 2019 CY - Berlin, Germany T2 - ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs T3 - 63 LA - english AB - In the main linac (ML) of the KEK-cERL, two superconducting cavities with high loaded Q (QL ¿ 1×107) are operated in continuous wave (CW) mode. It is important to control and suppress the microphonics detuning owing to the low bandwidth of the cavities. We evaluated the background microphonics detuning by the low level radio frequency system during the beam operation. Interestingly, a ¿field level dependence microphonics¿ phenomenon was observed on one of the cavities in the ML. Several frequency components were suddenly excited if the cavity field is above a threshold field (~3 MV/m). We found that this threshold field is probably related with the cavity quench limits despite the unclear inherent physical mechanism. Furthermore, in order to optimize the cavity resonance control system for better microphonics rejection, we have measured the mechanical transfer function between the fast piezo tuner and cavity detuning. Finally, we validated this model by comparing the model response with actual system response. PB - JACoW Publishing CP - Geneva, Switzerland SP - 48 EP - 51 KW - cavity KW - controls KW - LLRF KW - operation KW - linac DA - 2020/06 PY - 2020 SN - 978-3-95450-217-2 DO - doi:10.18429/JACoW-ERL2019-TUCOZBS04 UR - http://jacow.org/erl2019/papers/tucozbs04.pdf ER -