• L. Cooley, D. Burk, M. Ge, D.T. Hicks, C. Thompson, G. Wu
  Fermilab, Batavia

The local magnetic field will enhance at the edge of pits demonstrated by simulation results. Although cavity optical inspection systems provide a huge amount of information about surface features, the amount of topographic information is somewhat limited. Here, we report the use of two components silicone-based RTV for replicas that show increased details of topographic data associated with the optical cavity images. We show profilometry scans for replicas, which yield interesting details associated with equator welds and weld pits. The replicas provide contour information that can be used to evaluate mechanisms by which pits and other features limit RF performance. We also show that application of the replica followed by rinsing does not adversely affect the cavity performance.

• C.A. Cooper, J.S. Brandt, L. Cooley, M. Ge, E.R. Harms, T.N. Khabiboulline, J.P. Ozelis
  Fermilab, Batavia
• C. Boffo
  BNG, Würzburg

Fermi National Accelerator Lab is continuing to improve its infrastructure for research and development on the processing of superconducting radio frequency cavities. A single cell 3.9 GHz electropolishing tool built at Fermilab and operated at an industrial partner was recently commissioned. The EP tool was used to produce a single cell 3.9 GHz cavity that reached an accelerating gradient of 30 MV/m with a quality factor of 5 10⁹. A single cell 1.3 GHz cavity was also electropolished at the same industrial vendor using the vendor’s vertical full-immersion technique. On their first and only attempt the vendor produced a single cell 1.3 GHz cavity that reached 30 MV/m with a quality factor of 1 10¹⁰. These results will be detailed along with preliminary tumbling results.