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TY - CONF AU - Morishita, T. AU - Hasegawa, K. AU - Kondo, Y. AU - Oguri, H. AU - Otani, M. ED - Schaa, Volker RW ED - Pei, Guoxi ED - Chin, Yong Ho ED - Fu, Shinian ED - Zhao, Ning TI - Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling J2 - Proc. of LINAC2018, Beijing, China, 16-21 September 2018 CY - Beijing, China T2 - Linear Accelerator Conference T3 - 29 LA - english AB - The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described. PB - JACoW Publishing CP - Geneva, Switzerland SP - 798 EP - 801 KW - rfq KW - cavity KW - insertion KW - linac KW - simulation DA - 2019/01 PY - 2019 SN - 2226-0366 SN - 978-3-95450-194-6 DO - DOI: 10.18429/JACoW-LINAC2018-THPO049 UR - http://jacow.org/linac2018/papers/thpo049.pdf ER -