Sha, P. Zhai, J.Y. JACoW Geneva, Switzerland 978-3-95450-187-8 10.18429/JACoW-eeFACT2016-WET2H4 English 173-176 WET2H4 cavity ion niobium superconducting-cavity SRF Contribution to a conference proceedings 2017 2017-07 https://doi.org/10.18429/JACoW-eeFACT2016-WET2H4 http://jacow.org/eefact2016/papers/wet2h4.pdf In the recent decades, Superconducting cavities have been widely used to accelerate electron, positron, and ions. Most SRF cavities are made from bulk niobi-um till now, which has developed fast in the past years and is hard to advance more. Take 1.3 GHz 9-cell cavi-ty for example, the quality factor (Q) can keep above 10¹⁰ when the accelerating field (Eacc) reach 40 MV/m, which nearly touch the theoretical limitation of Q and Eacc for bulk niobium. For large superconducting accelerators in future (FCC, CEPC, etc), Q and Eacc should be increased significantly compared to now, which can reduce the cryogenic power and use fewer cavities. So new cavity material and techniques are being studied at accelerator laboratories, while Nitro-gen doping (N-doping) and Nb3Sn have developed quickly and been paid attention to mostly [1]. N-doping can increase Q by one time for 1.3 GHz 9-cell cavity, which have been adopted by Linac Coherent Light Source II (LCLS-II) at SLAC [2].