Magnetic flux studies in horizontally cooled elliptical superconducting cavities

Journal Article · Tue Jul 28 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4927519· OSTI ID:1213798

Martinello, M.; Checchin, M.; Grassellino, A.; Crawford, A. C. ; Melnychuk, O. ; Romanenko, A.; Sergatskov, D. A.

Previous studies on magnetic flux expulsion as a function of cooldown procedures for elliptical superconducting radio frequency (SRF) niobium cavities showed that when the cavity beam axis is placed parallel to the helium cooling flow and sufficiently large thermal gradients are achieved, all magnetic flux could be expelled and very low residual resistance could be achieved. In this paper, we investigate flux trapping for the case of resonators positioned perpendicularly to the helium cooling flow, which is more representative of how SRF cavities are cooled in accelerators and for different directions of the applied magnetic field surrounding the resonator. We show that different field components have a different impact on the surface resistance, and several parameters have to be considered to fully understand the flux dynamics. A newly discovered phenomenon of concentration of flux lines at the cavity top leading to temperature rise at the cavity equator is presented.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1213798
• Alternate ID(s): OSTI ID: 1214093; OSTI ID: 1420643
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Vol. 118 Journal Issue: 4; ISSN 0021-8979
• Publisher: American Institute of Physics
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
magnetic fields
cavitation
magnetic flux
superconductivity
surface dynamics