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Title: Magnetic flux studies in horizontally cooled elliptical superconducting cavities

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.
Authors:
;  [1] ;  [2] ; ; ; ; ;  [1]
  1. Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22494656
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 4; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABUNDANCE; COOLING; HELIUM; MAGNETIC FIELDS; MAGNETIC FLUX; NIOBIUM; RADIOWAVE RADIATION; SUPERCONDUCTING CAVITY RESONATORS; TEMPERATURE GRADIENTS