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Title: Effect of cathode shape on vertical buffered electropolishing for niobium SRF cavities

This paper reports the research results of the effect of cathode shape during vertical buffered electropolishing (BEP) by employing a demountable single cell niobium (Nb) superconducting radio frequency (SRF) cavity. Several different cathode shapes such as, for instance, bar, ball, ellipsoid, and wheels of different diameters have been tested. Detailed electropolishing parameters including I–V characteristic, removal rate, surface roughness, and polishing uniformity at different locations inside the demountable cavity are measured. Similar studies are also done on conventional electropolishing (EP) for comparison. It is revealed that cathode shape has dominant effects for BEP especially on the obtaining of a suitable polishing condition and a uniform polishing rate in an Nb SRF single cell cavity. EP appears to have the same tendency. This paper demonstrates that a more homogeneous polishing result can be obtained by optimizing the electric field distribution inside the cavity through the modification of the cathode shape given the conditions that temperature and electrolyte flow are kept constant. Electric field distribution and electrolyte flow patterns inside the cavity are simulated via Poisson–Superfish and Solidworks respectively. Finally, with the optimal cathode shape, BEP shows a much faster polishing rate of ~2.5 μm/min and is able to produce a smoothermore » surface finish in the treatments of single cell cavities in comparison with EP.« less
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Publication Date:
OSTI Identifier:
Report Number(s):
JLAB-ACC-13-1665; DOE/OR/23177-2655
Journal ID: ISSN 0169-4332
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Surface Science; Journal Volume: 280; Journal Issue: C
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE Niobium SRF cavities; Buffered electropolishing; Electropolishing; I–V characteristics