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TY - CONF AU - Venturini Delsolaro, W. AU - Miyazaki, A. ED - Pei, Guoxi ED - Schaa, Volker RW ED - Chin, Yong Ho ED - Fu, Shinian ED - Zhao, Ning TI - Seamless Quarter Wave Resonators for HIE ISOLDE J2 - Proc. of LINAC2018, Beijing, China, 16-21 September 2018 CY - Beijing, China T2 - Linear Accelerator Conference T3 - 29 LA - english AB - The HIE-ISOLDE post accelerator consists of 4 cryomodules with 5 niobium-coated Quarter Wave Reso-nators (QWR) each. The standard manufacturing tech-nique was to machine the inner and outer conductor sepa-rately, to shrink-fit the 2 pieces and to apply an electron beam welding at the interface. Due toμcracks, ob-served on some of the cavities around the welds, we took the decision to explore the possibility of a seamless de-sign. First cavities became available in late 2017 and were then cold-tested in the vertical cryostat. These seam-less coated quarter wave resonators have shown some of the highest Q-values of all HIE-ISOLDE cavities in the acceptance tests. Furthermore, we studied the cavity per-formance with different compensations of the earth mag-netic field and different temperature gradients upon cool down. These tests have demonstrated record-breaking RF surface fields for the Nb/Cu technology. This paper re-views the design and fabrication and reports on the cold tests results of seamless quarter wave resonators, and of possible future applications PB - JACoW Publishing CP - Geneva, Switzerland SP - 292 EP - 296 KW - cavity KW - ISOL KW - niobium KW - linac KW - cryomodule DA - 2019/01 PY - 2019 SN - 2226-0366 SN - 978-3-95450-194-6 DO - DOI: 10.18429/JACoW-LINAC2018-TU1A05 UR - http://jacow.org/linac2018/papers/tu1a05.pdf ER -