Field-Dependent Surface Resistance for Superconducting Niobium Accelerating Cavities - Condensed Overview of Weak Superconducting Defect Model

Small (compared to coherence length) weak superconducting defects when located at the surface, combined with the proximity and percolation effects, are claimed responsible for various observations with superconducting radio frequency (RF) accelerating cavities with nonconstant Q-value, such as Q-slope and Q-drop, the role of temperature, the result of nitrogen doping and its relation to the free path, and the influence of the static external magnetic field. The Ginzburg-Landau equations are used to confirm the results.

Automated summary

Small weak superconducting defects located at the surface, along with proximity and percolation effects, are found to be responsible for various observations in superconducting RF cavities. These include nonconstant Q-values, Q-slope and Q-drop, temperature effects, nitrogen doping, and the influence of external magnetic fields. The findings are confirmed using the Ginzburg-Landau equations.