JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
TY - CONF AU - Cano, A. AU - Bafia, D. AU - Grassellino, A. AU - Lee, J. AU - Martinello, M. AU - Romanenko, A.S. AU - Spina, T. AU - Sung, Z-H. ED - Saito, Kenji ED - Xu, Ting ED - Sakamoto, Naruhiko ED - Lesage, Ana ED - Schaa, Volker R.W. TI - On the Nature of Surface Defects Found in 2/0 N-Doped 9-Cell Cavities J2 - Proc. of SRF2021, East Lansing, MI, USA, 28 June-02 July 2021 CY - East Lansing, MI, USA T2 - International Conference on RF Superconductivity T3 - 20 LA - english AB - In this contribution, we present a systematic study on the microstructure of 1.3 GHz 9-cell TESLA type SRF cavity, processed with 2/0 Nitrogen-doping surface treatment, to explain the premature quench phenomena commonly observed in N-doping treated cavities. The microstructure characterization was carried out using Secondary electron images, advanced metallurgical techniques such as EBSD in parallel with chemical information obtained from spectroscopic techniques. The most remarkable difference is observed in the ends-cavities (1 and 9), which showed roughening of the surface, revealing a series of morphologies associated with Nb cubic phase. The cell-to-cell analysis also showed standard features such as pits with different geometry and distribution, located in grains and grain boundaries. The defects found in this system suggest that the standard electropolishing chemical etching was insufficient to eliminate history defects produced during the manufacture of the cavity, without discarding the role of the impurities, N and O, that could have induced the growth of these morphologies. PB - JACoW Publishing CP - Geneva, Switzerland SP - 336 EP - 338 KW - cavity KW - SRF KW - electron KW - survey KW - niobium DA - 2022/10 PY - 2022 SN - 2673-5504 SN - 978-3-95450-233-2 DO - doi:10.18429/JACoW-SRF2021-MOPFDV009 UR - https://jacow.org/srf2021/papers/mopfdv009.pdf ER -