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RIS citation export for MOPO130: Magnetic Flux Generated by Thermal Current in CEBAF 5-Cell Cavity System

AU  - Geng, R.L.
AU  - Huang, S.C.
ED  - Schaa, Volker RW
ED  - Pei, Guoxi
ED  - Chin, Yong Ho
ED  - Fu, Shinian
ED  - Zhao, Ning
TI  - Magnetic Flux Generated by Thermal Current in CEBAF 5-Cell Cavity System
J2  - Proc. of LINAC2018, Beijing, China, 16-21 September 2018
CY  - Beijing, China
T2  - Linear Accelerator Conference
T3  - 29
LA  - english
AB  - 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.
PB  - JACoW Publishing
CP  - Geneva, Switzerland
SP  - 273
EP  - 276
KW  - cavity
KW  - cryomodule
KW  - niobium
KW  - experiment
KW  - operation
DA  - 2019/01
PY  - 2019
SN  - 2226-0366
SN  - 978-3-95450-194-6
DO  - DOI: 10.18429/JACoW-LINAC2018-MOPO130
UR  - http://jacow.org/linac2018/papers/mopo130.pdf
ER  -