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Title |
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| TUPO030 |
Precise Evaluation of Characteristic of the Multi-layer Thin-film Superconductor Consisting of NbN and Insulator on Pure Nb Substrate |
cavity, radio-frequency, linac, SRF |
391 |
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- R. Katayama, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
- C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
- A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
- H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
- H. Ito
Sokendai, Ibaraki, Japan
- R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
- H. Oikawa
Utsunomiya University, Utsunomiya, Japan
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In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of the cavity with a multilayer thin-film structure that consists of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrating into the superconductor layer, and it is predicted to depend on the combination of the film thickness. We made samples that have NbN/SiO2 thin-film structure on pure Nb substrate with several thicknesses of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of the NbN sample with a thickness of 200 nm by using the third-harmonic voltage method. In addition, we report the preliminary results to evaluate the dependence of the effective Hc1 on the thickness of the NbN film in the range 50 nm-200 nm.
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Slides TUPO030 [0.305 MB]
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO030
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| About • |
paper received ※ 18 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 |
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| THPO002 |
Investigation of SRF Elliptical Cavities Made by New Nb Materials in KEK |
cavity, niobium, collider, SRF |
676 |
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- T. Dohmae, K. Umemori, Y. Watanabe, M. Yamanaka
KEK, Ibaraki, Japan
- T. Okada
Sokendai, Ibaraki, Japan
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Cost reduction for cavity fabrication is currently main issue to realize international linear collider. Cavity fabrication facility (CFF) in KEK is approaching this issue from a point of view of materials for cavities. CFF had fabricated SRF elliptical cavities made by two types of niobium; one is high tantalum contained and low RRR (< 100) fine grain niobium, and the other is high tantalum contained and RRR < 300 large grain (LG) niobium. Former was melted two times (normally five times) which results RRR recovery up to around 300, and used for cell parts. Two 3-cell cavities were fabricated for each material respectively and vertical tested. One of these cavity made by LG achieved accelerator gradients of more than 40 MV/m. In this report, cavity materials and vertical test results are presented in detail.
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| DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-LINAC2018-THPO002
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| About • |
paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 |
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| Export • |
reference for this paper using
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