Cavities - Fabrication
seamless technology
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MOP007 400 MHz Seamless Copper Cavity in the Framework of FCC Study 36
  • O. Azzolini, G. Keppel, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  In the framework of the FCC study the production of 400 MHz copper cavities is one of the key challenges for the development of more efficient superconducting RF cavities. Any progress on substrate manufacturing and preparation will have an immediate impact on the final RF performance, as it was demonstrated by the seamless cavities produced for the HIE-ISOLDE project. Spinning is a potential alternative to conventional production methods of copper single and multi-cells. In this work is presented the first 400 MHz copper SRF cavity prototype produced via Spinning at Laboratori Nazionali di Legnaro of INFN. The production process is explained starting from a copper foil of 1000 mm diameter and 4mm thick to arrive to a seamless 400 MHz cavity. Moreover, the metrology of the cavity and the analysis of the influence of intermediate thermal treatments among each steps of cold work are shown.  
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About • paper received ※ 23 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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Electrodeposition of Copper Applied to the Manufacture of Seamless SRF Cavities  
  • G.J. Rosaz, S. Atieh, S. Calatroni, L.M.A. Ferreira, E. Garcia-Tabares Valdivieso, C. Garion, L. Lain-Amador, A.T. Perez Fontenla, K. Scibor, M. Taborelli, C. Yin Vallgren
    CERN, Geneva, Switzerland
  Nb thin film SRF cavities have demonstrated for many years their strong potential as being an alternative to bulk Nb cavities [1]. However most of the defects observed in the Nb layers originate from defects inherited from the substrate itself [2]. Two routes are used to manufacture Cu cavities. The first one consists of forming the half-cells independently by either spinning or electro-hydroforming. The latter are then joined together and to the cut-offs by electron-beam welding. The second one is a seamless process in which the cell is entirely spun around a mandrel and then electron-beam welded to the cut-offs. Both approaches require welding, leading to potential formation of porosities. We propose an innovative route, inspired from a technology used to form small diameter vacuum chambers [3]. The cavity is formed by electrodeposition of Cu on a sacrificial mandrel whose surface state will determine the inner cavity’s surface quality. The strength of the process relies on the total absence of welding. We present the values obtained for Young Modulus, Ultimate Tensile Stress, roughness and RRR on dedicated samples. We will then discuss the fabrication route of a real cavity.
[1] C. Benvenuti et al., IEEE transactions on applied superconductivity, vol. 9, No. 2, June 1999.
[2] G. Rosaz et al., FCC week 2018
[3] L. Lain Amador et al., JVSTA, vol. 36, pp. 021601, 2018.
slides icon Slides FRCAB2 [9.174 MB]  
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