PAC 2005 - List of Authors

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Singer, X.

Paper	Title	Page
TPPT075	Influence of Ta Content in High Purity Niobium on Cavity Performance	3955
	P. Kneisel, G. Ciovati, G. Myneni Jefferson Lab, Newport News, Virginia T. Carneiro Reference Metals, Bridgeville, Pennsylvania D. Proch, W. Singer, X. Singer DESY, Hamburg
	Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150. In a previous paper* we have reported about initial tests of single cell 1500 MHz cavities made from high purity niobium with three different Ta contents of 160 ppm, ~600 ppm and ~1400 ppm. These cavities had been treated by buffered chemical polishing several times and 100 mm, 200 mm and 300 mm of material had been removed from the surfaces. This contribution reports about subsequent tests following post purification heat treatments with Ti and “in situ” baking. As a result, all cavities exhibited increased quench fields due to the improved thermal conductivity after the heat treatment. After the "in situ" baking at 120C for ~40 hrs the always present Q-drop at high fields disappeared and further improvements in accelerating gradient could be realized. Gradients as high as Eacc = 35 MV/m were achieved and there were no clear indications that the cavity performance was influenced by the Ta content in the material. A multi-cell cavity from the high Ta content material is being fabricated and results will be presented at this conference. *P. Kneisel et al., Linac 2004.

Paper

Title

Page

TPPT075

Influence of Ta Content in High Purity Niobium on Cavity Performance

3955

P. Kneisel, G. Ciovati, G. Myneni
Jefferson Lab, Newport News, Virginia
T. Carneiro
Reference Metals, Bridgeville, Pennsylvania
D. Proch, W. Singer, X. Singer
DESY, Hamburg

Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

In a previous paper* we have reported about initial tests of single cell 1500 MHz cavities made from high purity niobium with three different Ta contents of 160 ppm, ~600 ppm and ~1400 ppm. These cavities had been treated by buffered chemical polishing several times and 100 mm, 200 mm and 300 mm of material had been removed from the surfaces. This contribution reports about subsequent tests following post purification heat treatments with Ti and “in situ” baking. As a result, all cavities exhibited increased quench fields due to the improved thermal conductivity after the heat treatment. After the "in situ" baking at 120C for ~40 hrs the always present Q-drop at high fields disappeared and further improvements in accelerating gradient could be realized. Gradients as high as Eacc = 35 MV/m were achieved and there were no clear indications that the cavity performance was influenced by the Ta content in the material. A multi-cell cavity from the high Ta content material is being fabricated and results will be presented at this conference.

*P. Kneisel et al., Linac 2004.