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Passivated niobium cavities

United States Patent

December 19, 2006
View the Complete Patent at the US Patent & Trademark Office
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A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.
Myneni; Ganapati Rao (Yorktown, VA), Hjorvarsson; Bjorgvin (Lagga Arby, SE), Ciovati; Gianluigi (Newport News, VA)
Jefferson Science Associates LLC (Newport News, VA)
11/ 168,198
June 28, 2005
The United States of America may have certain rights to this invention under Management and Operating Contract No. DE-AC05-84ER 40150 from the Department of Energy.