New kind of beam pipe for rapid cycling proton synchrotrons

A thin metallic beam pipe reinforced by multi-layer spiral metallic ribs is proposed for rapid cycling proton synchrotrons. The pipe is made of Inconel 718 with thickness of a few tenths of nuts. Each spiral rib has a cross section of about 0.3 mm² and can be bonded to the pipe by using laser deposition technique (e.g., precision metal deposition, or PMD). Compared with other designs (e.g.., ceramic beam pipe with a metallic cage used in the ISIS at the RAL), this new pipe will reduce the magnet aperture significantly, which, in turn, reduces the construction and operating cost of a synchrotron. Numerical simulations and analytical modeling are used to investigate the structural strength and deformation, and the eddy current effects, including heating, magnetic field distortion and the electro-magnetic force on the beam pipe. The results show that this new beam pipe will work. It can be employed to high intensity rapid cycling proton synchrotrons, such as the proton driver at FERMILAB and the JHF at JAERI/KEK. Effort to build a prototype is under way.