| Title |
Thermal Contact Resistance at the Nb-Cu Interface |
| Authors |
- V. Palmieri
INFN/LNL, Legnaro (PD), Italy
- R. Vaglio
UniNa, Napoli, Italy
|
| Abstract |
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.
|
| Funding |
Work performed thanks to the financement in Italy by the INFN 5th group for Accelerator and Applied Physics |
| Paper |
download TUBA02.PDF [0.955 MB / 6 pages] |
| Slides |
download TUBA02_TALK.PDF [18.857 MB] |
| Conference |
SRF2015, Whistler, BC, Canada |
| Series |
International Conference on RF Superconductivity (17th) |
| Proceedings |
Link to full SRF2015 Proccedings |
| Session |
Fundamentals II - Beyond Nb |
| Date |
15-Sep-15 10:40–13:00 |
| Main Classification |
Fundamentals SRF R&D - Other Materials |
| Keywords |
cavity, interface, niobium, feedback, superconductivity |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Robert E. Laxdal (TRIUMF, Vancouver, BC, Canada); Jana Thomson (TRIUMF, Vancouver, BC, Canada); Volker RW Schaa (GSI, Darmstadt, Germany) |
| ISBN |
978-3-95450-178-6 |
| Published |
December 2015 |
| Copyright |
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