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TY - CPAPER AU - Palmieri, V. AU - Vaglio, R. TI - Thermal Contact Resistance at the Nb-Cu Interface J2 - Proc. of International Conference on RF Superconductivity (SRF2015), Whistler, BC, Canada, Sept. 13-18, 2015 AB - Niobium thin film sputtered copper cavities are strongly limited for the application in high field accelerators by the unsolved “Q-slope” problem. In the present paper, we examine the different contributions of the niobium film, the copper substrate, the Helium-Copper interface and the Niobium-Copper Interface, proposing the hypothesis that main cause of losses is due to an enhanced thermal boundary resistance RNb/Cu at the Nb/Cu interface, due to poor thermal contact between film and substrate. So, starting from different Q vs Eacc experimental curves from different sources, and using a typical “inverse problem” method, we deduced the corresponding distribution functions generating those curves. Assuming that only a small fraction of the film over the cavity surface is in poor thermal contact with the substrate (or even partially detached), due to bad adhesion problems, we propose as a possible solution of the problem, the possibility to use higher temperatures of deposition and the adoption at the interface of a buffer layer of a material that alloys both with Copper and with Niobium. PB - JACoW CY - Geneva, Switzerland SP - 488 EP - 493 KW - cavity KW - interface KW - niobium KW - feedback KW - superconductivity DA - 2015/12 PY - 2015 SN - 978-3-95450-178-6 DO - 10.18429/JACoW-SRF2015-TUBA02 UR - http://srf2015.vrws.de/papers/tuba02.pdf ER -