Speaker
Eric Lechner
(Thomas Jefferson National Accelerator Facility)
Description
Atomic force microscopy is used to compare the characteristic surface topographies of electropolished bulk Nb, Nb films deposited on Cu, and Nb3Sn. The role of defect geometry in magnetic field enhancement and superheating field suppression is examined using the London model. Although simple roughness metrics are widely used to assess superconducting radio frequency materials, these parameters do not identify the features most relevant to achievable peak magnetic fields. The influence of shallow impurity profiles on magnetic field enhancement at nanoscale defects is also examined. These results motivate the adoption of surface roughness analyses that more directly reflect the influence of surface roughness on high-field performance.
Author
Eric Lechner
(Thomas Jefferson National Accelerator Facility)