Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around T{sub c}

Journal Article · Wed May 14 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4875655· OSTI ID:22275574

Melnychuk, O.; Sergatskov, D. A. ^[1]

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1. Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

We report a strong effect of the cooling dynamics through T{sub c} on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120 °C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance, while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.

• OSTI ID: 22275574
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 18; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COOLING
ELECTRIC CONDUCTIVITY
ELECTROPOLISHING
MAGNETIC FIELDS
MAGNETIC FLUX
MONOCRYSTALS
NIOBIUM
NITROGEN
RADIOWAVE RADIATION
SUPERCONDUCTING CAVITY RESONATORS
SUPERCONDUCTORS
SURFACE TREATMENTS
TRANSITION TEMPERATURE
TRAPPING