Large-aperture alumina ceramics beam pipes with titanium bellows for the rapid cycling synchrotron at Japan Proton Accelerator Research Complex
The 3-GeV rapid-cycling synchrotron at the Japan Proton Accelerator Research Complex aims to generate proton beams whose power output is among the highest in the world, reaching an extraction beam power of 1 MW. Beam pipes fabricated using alumina ceramics are used to prevent the formation of eddy c...
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| Published in: | Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vol. 36; no. 3 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
01-05-2018
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| Online Access: | Get full text |
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| Summary: | The 3-GeV rapid-cycling synchrotron at the Japan Proton Accelerator Research Complex aims to generate proton beams whose power output is among the highest in the world, reaching an extraction beam power of 1 MW. Beam pipes fabricated using alumina ceramics are used to prevent the formation of eddy currents caused by the rapid magnetic field changes. The residual radioactive dose is higher in the beam-injection area than in other areas. In this area, ceramics beam pipes in a quadrupole magnet and a horizontal bump magnet are directly connected without bellows because of space limitations. Improvement of the maintainability of such areas is the first priority for minimizing the radiation exposure of maintenance workers. The ceramics beam pipe in the quadrupole magnet was custom designed to have bellows on both ends. The shapes of the ceramics end unit ducts and titanium sleeves of the pipe was revised to allow a 30-mm long space for inserting the bellows. The ceramics unit ducts and titanium sleeves with unique cross-sectional shapes, i.e., racket shape that fits into 500 mm to accept the injecting beam and a circulating beam passing through the quadrupole magnet at the beam-injection area, respectively, were successfully produced. Using a set of unit ducts and a sleeve, reliable brazing conditions and deformation under atmospheric pressure within the elastic displacement region were achieved. Reliable brazing was obtained by the vacuum improvement in the brazing furnace. Deformation by atmospheric pressure was within the elastic displacement. Outgassing rate and the gas components were verified using ceramics samples that were treated under the same conditions as the unit ducts. Large-aperture titanium bellows with low spring constants were successfully produced by mechanical forming. All of the components of the beam pipe have already been produced successfully, and the manufacturing process is currently in progress. |
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| ISSN: | 0734-2101 1520-8559 |
| DOI: | 10.1116/1.5023350 |