Paper |
Title |
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MOPO130 |
Magnetic Flux Generated by Thermal Current in CEBAF 5-Cell Cavity System |
273 |
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- R.L. Geng
JLab, Newport News, Virginia, USA
- S.C. Huang
IMP/CAS, Lanzhou, People’s Republic of China
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The unloaded quality factor Q0 of many 5-cell CEBAF cavities were lowered by a factor of ~2 from their vertical qualification testing to their beam operation in CEBAF tunnel. Causes of this Q0 degradation were studied previously, including a more recent one addressing static fluxes arising from magnetic components near a 5-cell cavity. This paper reports on a preliminary study of the dynamic fluxes generated by a thermal current. Such a thermal current arises from the Seebeck effect and flows in closed loops formed by a niobium cavity and its surrounding tuner rods and liquid helium vessel that are made of stainless-steel. The behaviors of magnetic fluxes in response to various thermal profiles on a 5-cell CEBAF cavity with integrated tuner rods were studied in a JLAB VTA dewar. An outcome of this study is a proposed cool-down procedure for eliminating the thermal current generated magnetic fluxes around 5-cell cavities placed in CEBAF tunnels. This procedure may be useful to improve cavity Q0 in a cost-effective manner, which in turn saves cryogenic expenditures for sustaining CEBAF operation.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO130
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About • |
paper received ※ 01 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019 |
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TUPO036 |
Vertical Test Results of Plasma In-situ Cleaning on Low Beta HWR Cavity |
408 |
TUOP06 |
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- A.D. Wu, H. Guo, Y. He, C.F. Hu, S.C. Huang, C.L. Li, Y.M. Li, X. Liu, F. Pan, Y.K. Song, P.R. Xiong, L. Yang, W.M. Yue, C. Zhang, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China
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Field emission occurred in SRF cavity is the major limitation to operate at high gradient with stability. The plasma in-situ cleaning for the low beta HWR cavity was carried out to remove the hydrocarbons contaminants on the inner cavity surface. And the vertical test results indicated that the field emission effect was relieved with the increasing of the quench point and emission set-on point. Thus, oxygen active plasma processing can be an effective method to solve the field emission issues for the low beta HWR cavity.
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Slides TUPO036 [1.281 MB]
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Poster TUPO036 [0.672 MB]
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO036
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About • |
paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019 |
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THPO069 |
The Electromagnetic Optimization of TE-sample Host Cavity at IMP |
852 |
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- S.C. Huang, Y. He, T. Tan, S.X. Zhang
IMP/CAS, Lanzhou, People’s Republic of China
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As a part of the research and development work of thin-film materials for superconducting radio frequency(SRF) application in future accelerators at IMP, a 3.9GHz TE sample host cavity is being developed for the purpose of characterizing the RF Property and the loss mechanism of thin-film materials, which operates in the TE011 mode and accommodates disk sample with 110mm diameter, theoretically, the maximum magnetic field on sample surface will go up to 100mT, the resolution of surface resistance on sample will below nOhm by using thermometry technique( T-Mapping). In this paper, the electromagnetic optimization result of TE-sample host cavity will be presented, and the design consideration of hook tip style coupler and T-mapping system are also discussed.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-LINAC2018-THPO069
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About • |
paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019 |
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