| Title |
Improvement of Magnetic Condition for KEK-STF Vertical Test Facility Toward High-Q Study |
| Authors |
- K. Umemori, T. Dohmae, E. Kako, T. Konomi, T. Kubo, M. Masuzawa, G.-T. Park, A. Terashima, K. Tsuchiya, R. Ueki
KEK, Ibaraki, Japan
- T. Okada
Sokendai, Ibaraki, Japan
|
| Abstract |
Improvement of unloaded Q-values of SRF cavities are important to reduce surface loss of cavity and heat loads of He refrigerators. R&D activities have been developed worldwide. We also started work toward high-Q, but soon realized that magnetic condition of KEK-STF vertical test facility was not good enough to carry out high-Q measurements. First, magnetized components were searched. Shafts to move variable coupler were found to be most magnetized one and exceed more than 1 Gauss. Magnetized components were exchanged to non-magnetized one. In order to further reduce remnant magnetic field, a solenoid coil was prepared and used to cancel it. To suppress flux trapping, a heater was located around an upper beampipe of cavity and made thermal gradient. Owing to these efforts, Q-value of more than 1x10¹¹ can be measured with a condition of residual resistance of ~3 nΩ. Clear flux expulsion signal can be also observed. In this presentation, we report about efforts to reduce ambient magnetic field and to realize high-Q measurements. Results of vertical tests, including flux expulsion measurements, are also presented.
|
| Paper |
download TUPB028.PDF [0.875 MB / 4 pages] |
| Poster |
download TUPB028_POSTER.PDF [1.961 MB] |
| Export |
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| Conference |
SRF2017, Lanzhou, China |
| Series |
International Conference on RF Superconductivity (18th) |
| Proceedings |
Link to full SRF2017 Proccedings |
| Session |
Poster Session |
| Date |
18-Jul-17 14:00–17:00 |
| Main Classification |
SRF Technology R&D |
| Sub Classification |
Cavity |
| Keywords |
ion, cavity, solenoid, SRF, controls |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Volker RW Schaa (GSI, Darmstadt, Germany); Yuan He (IMP, Lanzhou, China); Lu Li (IMP, Lanzhou, China); Ning Zhao (IHEP, Beijing, China) |
| ISBN |
978-3-95450-191-5 |
| Published |
January 2018 |
| Copyright |
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