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Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Energy Research, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
2.18 Megabytes : digital, PDF file
Additional Creators
United States. Department of Energy. Office of Energy Research and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
The positron and electron linacs of the International Linear Collider (ILC) will require over 14,000, nine-cell, one meter length, superconducting radio frequency (SRF) cavities [ILC Reference Design Report, 2007]. Manufacturing on this scale will benefit from more efficient fabrication methods. The current methods of fabricating SRF cavities involve deep drawing of the halves of each of the elliptical cells and joining them by high-vacuum, electron beam welding, with at least 19 circumferential welds per cavity. The welding is costly and has undesirable effects on the cavity surfaces, including grain-scale surface roughening at the weld seams. Hydroforming of seamless tubes avoids welding, but hydroforming of coarse-grained seamless tubes results in strain-induced surface roughening. Surface roughness limits accelerating fields, because asperities prematurely exceed the critical magnetic field and become normal conducting. This project explored the technical and economic feasibility of an improved processing method for seamless tubes for hydroforming. Severe deformation of bulk material was first used to produce a fine structure, followed by extrusion and flow-forming methods of tube making. Extrusion of the randomly oriented, fine-grained bulk material proceeded under largely steady-state conditions, and resulted in a uniform structure, which was found to be finer and more crystallographically random than standard (high purity) RRR niobium sheet metal. A 165 mm diameter billet of RRR grade niobium was processed into five, 150 mm I.D. tubes, each over 1.8 m in length, to meet the dimensions used by the DESY ILC hydroforming machine. Mechanical properties met specifications. Costs of prototype tube production were approximately twice the price of RRR niobium sheet, and are expected to be comparable with economies of scale. Hydroforming and superconducting testing will be pursued in subsequent collaborations with DESY and Fermilab. SRF Cavities are used to construct particle accelerators for high-energy physics research, as well as for lower energy particle accelerators, and Free Electron Lasers. These machines have applications in the fields of basic science, industrial processing, medical diagnostics, pharmaceutical research and weapons systems. The scientific community and the general public will benefit from the implementation of this technology since lower production costs will increase the availability of SRF particle accelerators.
Report Numbers
E 1.99:doe/er/83909-2
doe/er/83909-2
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
10/31/2009.
"doe/er/83909-2"
Roy Crooks, Ph.D., P.E.
Black Laboratories, L.L.C.
Type of Report and Period Covered Note
Final; 07/01/2005 - 09/30/2009
Funding Information
FG02-04ER83909
View MARC record | catkey: 14445241