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| WEPMB016 | Vertical Test Results of Nitrogen Doped SRF Cavities at KEK | 2154 |
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| Recently Nitrogen doping(N-doping) technique was proposed and drastic improvements of Q-values were reported. Since high-Q operation of SRF cavities are very attractive for CW machine, we started investigation on performance of Nitrogen doped SRF cavities. Nitrogen doping systems were prepared on two vacuum furnaces, which have been used for annealing of SRF cavities. Two fine grain single cell cavities have been used for the study. After 800 degree, 3 hours annealing, N-doping were carried out under several Pa of Nitrogen pressure and followed by post annealing. Three kind of different conditions, pressure and duration time, were attempted. After applying EP-2, cavity performances were evaluated by vertical tests. Against our expectations, we observed lower Q-values, at every measurements, than those measured without N-doping. In this presentation, we describe details about N-doping system and parameters and results obtained by vertical tests. Some discussions are also given against our results. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB016 | |
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| WEPMB018 | Multipactor Simulations in 650 MHz Superconducting Spoke Cavity for an Electron Accelerator | 2161 |
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Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. In order to realize a compact industrial-use X-ray source based on the laser-Compton scattering, a superconducting spoke cavity for an electron accelerator operated at 4K is under development. While the initially proposed operating frequency was 325MHz considering the 4K operation, we decided to start from the half scale model at 650MHz to accumulate our production experience of spoke cavity within our limited resources. In the present contribution, procedures and results of multipactor simulations for 650MHz spoke cavities are briefly introduced. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB018 | |
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| WEPMB019 | Magnetic Fields in Bulk, Film, and Multilayer Superconductors in Front of a Multi-turn Coil | 2164 |
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Funding: JSPS Young Scientists(B) #26800157, JSPS Challenging Exploratory Research #26600142, MEXT Photon and Quantum Basic Research Coordinated Development Program The magnetic field distribution formulae in a bulk superconductor, a superconducting film, and an SIS multilayer structure in front of a multi-turn coil are derived, which may be useful for a detailed analysis in a vortex field measurement by using the third harmonic method. * See for example the invited oral presentation by T. Kubo, "Theory of multilayer coating for proof-of-concept experiments", at SRF2015 ** C.Z.Antoine et al., Appl. Phys. Lett. 102, 102603 (2013) |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB019 | |
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| WEPMB021 | Construction of Measurement System for Superconducting Characteristics on Thin-film Samples at KEK | 2167 |
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| We set up a measurement system for superconducting characteristics on thin-film samples at KEK. The system includes small-sized and middle-sized cryostats, where critical temperature, critical magnetic field, Residual Resistiviy Ratio (RRR), Superconducting RF (SRF) resistivity can be measured on thin-film samples. A small-sized cryostat has a compact refrigerator to cool down samples for the measurements of critical temperature and RRR. On the other had, we can cool down various setups with a middle-sized cryostat by using liquid helium. A thin-film sample is set into a mushroom cavity and the SRF characteristics of the thin-film sample can be measured. In another setup, a sample is set with a small coil and the third harmonic measurement is done on the sample around the critical temperature. Finally, a thin-film sample is set into the bore-center of superconducting magnet and the magnetization of sample is measured with external magnetic field around the critical temperature. This article presents the details of the system and some measurements of samples by the system. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB021 | |
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| WEPMB024 | Study on Nondestructive Inspections for Super-conducting Cavity | 2174 |
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Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have been studying nondestructive inspections for super-conducting spoke cavities. The temperature mapping (T-map) and X-ray mapping (X-map) are powerful inspection methods to locate a hot spot during the vertical RF tests. There would be a defect under the hot spot and the defect may be the cause of a quench. Our XT-map system (a combined system of T-map and X-map) has a high resolution in space. Because the huge amount of sensor signals are multiplexed at a hi-speed scanning rate in the vicinity of the sensors, the small number of signal lines makes the installation process easy and reduces the system complexity. Our XT-map got useful results on finding a defect in vertical RF tests of International Linear collider super-conducting cavity. The XT-map system is useful as low cost nondestructive inspections for superconducting spoke cavity. The study will be reported. progresses will be reported. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB024 | |
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| WEPMB025 | Fabrication of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources | 2177 |
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Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and γ-ray sources in academic and industrial applications, we adopt the super-conducting spoke cavity to electron beam drivers. The spoke cavity has advantages such as relative compactness in comparison with an elliptical cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, the better packing in a linac to install couplers on outer conductor. On the other hand the spoke cavity has disadvantage of more complicated structure than an elliptical cavity. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we have begun to fabricate the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. In this paper, we present our fabrication status. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB025 | |
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