Development of a Niobium Bellow for Beamline Connections [electronic resource].

Published: Washington, D.C. : United States. Dept. of Energy. Office of Energy Research, 2003.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description: 417 Kilobytes pages : digital, PDF file
Additional Creators: Thomas Jefferson National Accelerator Facility (U.S.), 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

Superconducting cavities in an accelerator assembly are usually connected at the beampipes by stainless steel bellows. The bellows operate at an intermediate temperature, compensating for alignment tolerances on the cavity beamlines and for thermal contraction during cooldown to cryogenic temperatures. This transition from one cavity to the next in a cavity string is typically of the order of 3/2 wavelength long with approximately half a wavelength taken up by the bellows. If one could incorporate a niobium bellows in the beam pipe, this distance could be reduced by half a wave length. In the case of a big accelerator such as TESLA the overall cavity length for the accelerator could be reduced by roughly 10% or 2000 m. In terms of cost savings this would amount to several million dollars. Motivated by this we have begun to develop a niobium bellows to be used on a 2.75 inch diameter beamline. It is made from 0.3 mm thick niobium sheet, rolled into a tube and secured by a longitudinal full penetration electron beam weld. The weld is made at high speed with a narrow, focused beam reducing the heat affected zone, thus limiting the grain growth, which could affect the formability. Subsequently, two convolutions are pressed into this tube in a 2-stage process, using an external die and a polyurethane internal expander. Niobium cuffs and flanges are electron beam welded to the formed bellows, which facilitates leak testing and allows some measurements of compression/expansion and bending. In this contribution the fabrication process and the subsequent mechanical and vacuum tests with the bellows will be described.

Report Numbers

E 1.99:jlab-acc-03-194
E 1.99: doe/er/40150-2576
doe/er/40150-2576
jlab-acc-03-194

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Note

Published through SciTech Connect.
09/01/2003.
"jlab-acc-03-194"
" doe/er/40150-2576"
11th Workshop on RF Superconductivity, Travenmunde, Lubeck (DE), 09/08/2003--09/12/2003.
Peter Kneisel; John Brawley; Larry Turlington; Robert Manus; Stephen Manning; Samuel Morgan; Gary Slack.

Funding Information

AC05-84ER40150

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