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Nb/sub 3/Sn coating of high purity Nb cavities

Conference · · IEEE Trans. Magn.; (United States)
OSTI ID:6091088
Superconducting Nb cavities fabricated from high purity sheet material or postpurified by solid state gettering with Y or Ti provide high field and Q/sub 0/ levels due to the thermal stabilization of defects. For accelerator applications especially at frequencies above 1 GHz the coating of such cavities with Nb/sub 3/Sn layers is challenging because of significantly reduced rf losses at operating temperatures of about 4.2 K. The authors have developed a modified vapor diffusion technique using specially constructed UHV furnaces to produce uniform Nb/sub 3/Sn layers on 1 and 3 GHz accelerator cavities without losing the high thermal conductivity of the Nb wall. In a first experiment with a single-cell 3 GHz cavity of medium Nb purity (RRR=156) the authors have achieved E/sub acc/=10 MV/m with an 0.6 ..mu..m thick Nb/sub 3/Sn layer. This is so far the highest accelerating field for our Nb/sub 3/Sn cavities but it is low compared to the 25 MV/m achieved in the same cavity before coating. Possible reasons for the reduced breakdown field for Nb/sub 3/Sn will be discussed on the basis of the local thermal breakdown model.
Research Organization:
6996600
OSTI ID:
6091088
Report Number(s):
CONF-880812-
Conference Information:
Journal Name: IEEE Trans. Magn.; (United States) Journal Volume: 25:2
Country of Publication:
United States
Language:
English