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TY - CONF AU - Yang, Z.Q. AU - He, Y. AU - Pan, F. ED - Pei, Guoxi ED - Schaa, Volker RW ED - Chin, Yong Ho ED - Fu, Shinian ED - Zhao, Ning TI - Several Experimental Phenomena of Sn Nucleation on Nb Surface Observed at IMP J2 - Proc. of LINAC2018, Beijing, China, 16-21 September 2018 CY - Beijing, China T2 - Linear Accelerator Conference T3 - 29 LA - english AB - Nucleation process is an important step that affects the quality of Nb3Sn films coated by vapor diffusion method. A uniform distribution of nucleation centers is essential to the uniformity of Nb3Sn films. In this paper we report several experimental phenomena on the Sn nucleation on Nb surface. Better nucleation in the downstream of the pumping direction was observed. Influence of SnCl2 partial pressure inhomogeneity was studied. Samples with higher SnCl2 partial pressure have denser nucleation, which means homogeneous SnCl2 pressure is a critical factor to the uniform nucleation. Less-nuclear zones, mainly distributed at cracks, grain boundaries and even some whole grain surfaces, were found on the surfaces of all samples. The less-nuclear zones may result in the low tin regions of the Nb3Sn cavities. The specific solution to the less-nuclear problem was proposed. These studies help to better understanding of the mechanism underlying the nucleation process and will be useful foundation for the follow-up Nb3Sn/Nb project at IMP. PB - JACoW Publishing CP - Geneva, Switzerland SP - 412 EP - 416 KW - cavity KW - experiment KW - SRF KW - HOM KW - niobium DA - 2019/01 PY - 2019 SN - 2226-0366 SN - 978-3-95450-194-6 DO - DOI: 10.18429/JACoW-LINAC2018-TUPO038 UR - http://jacow.org/linac2018/papers/tupo038.pdf ER -