Enhancement in Quality Factor of SRF Niobium Cavities by Material Diffusion

Pashupati Dhakal, Gianluigi Ciovati, Peter Kneisel, and Ganapati Rao Myneni

Jefferson Lab, Newport News VA, USA

Email:  [email protected]

Abstract – High quality factor of superconducting radio frequency (SRF) cavities in medium field range (~20 MV/m) is desired for future continuous wave accelerator machines to reduce the operating cryogenic loss by reducing the surface resistance. The surface resistance in superconducting materials is the sum of the temperature independent residual resistance and temperature dependent BCS resistance. The surface resistance can be minimized by using several processing technique as well as selectively doping other material in the inner surface of SRF cavities. The increase in quality factor called as Q-rise has been observed in the cavities where titanium was thermally diffused on inner cavity surface. Here, we present the results of recent measurement on the cavity performances where titanium and nitrogen were diffused in SRF niobium.

Keywords (Index Terms) – Quality Factor, Material Diffusion, Niobium, SRF cavities

Acknowledgements: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2015.
Received August 14, 2014; Selected September 18, 2014. Reference ST416; Category 5, 6.
ASC 2014 talk 1LOr1B-05: manuscript published online in IEEE Trans. Appl. Supercond. (IEEE XPLORE)
DOI: 10.1109/TASC.2014.2359640, on September 22, 2014.