Vertical Electropolishing of 1.3 GHz Niobium Nine-cell SRF Cavity: Bulk Removal and RF Performance

Vijay Chouhan, Hitoshi Hayano, Yoshiaki Ida, Hayato Ito, Shigeki Kato, Hideaki Monjushiro, Keisuke Nii, Hiroki Oikawa, Takayuki Saeki, Motoaki Sawabe, Takanori Yamaguchi, Chin, Yong Ho (Ed.) (+4 others)
Vertical electropolishing (VEP) technique have been successfully developed for 1.3 GHz niobium (Nb) single cell cavity to achieve a smooth surface with uniform removal and better RF performance as achieved after horizontal EP (HEP) process. VEP parameters for 1.3 GHz Nb nine-cell cavities are being studied using a nine-cell coupon cavity and our unique Ninja cathode. The investigated VEP parameters heretofore were applied on a 1.3 GHz Tesla shape nine-cell superconducting RF cavity for bulk
more » ... cavity for bulk removal of 100 µm followed by fine removal of 20 and 10 µm. The interior surface was found to be smooth and shiny after the VEP process. Our recently developed dual flow technique, in which the EP acid is flown separately in the Ninja cathode housing and cavity, yielded lower asymmetry in removal along the cavity length. The cavity was tested in a vertical cryostat after the final VEP process. The cavity achieved 28.3 MV/m at Q0 value of 6.7x109. The cavity performance was almost the same as in the baseline vertical test performed after the HEP process.
doi:10.18429/jacow-linac2018-tupo068 fatcat:7g7kk6fd3bawroaqqsew2u63sy