Speaker
Description
The Continuous Electron Beam Accelerator Facility (CEBAF) upgrade of the energy from 12 GeV to 22 GeV with a single Fixed Field Alternating (FFA) gradient arc requires time-of-flight and adjustments of the momentum compaction dependence on energy or M56 using multiple splitters.To reduce these dependences from the present FFA-FODO type design, with linear transverse magnetic field dependence, two different arc lattice designs are considered: (1) First an attempt to make an isochronous FFA arc design in the whole energy range between 9.6-22 GeV and the (2) second to use a lattice by adding additional sextupole magnetic field component to the magnets. In the first attempt we constructed 27 isochronous modules in each arc containing eight variable combined function magnets. The isochronous condition was established at the reference energy by obtaining zero momentum compaction by making the dispersion function to oscillate between positive and negative values in each module. Orbits within the whole energy range between 9.6 and 22.6 GeV also oscillate around the central circular reference orbit following the dispersion function oscillations. This approach reduces the emittance of the electron beam (the H-function) and might be applicable for the future electron ion colliders. The second approach in the arc lattice design was abandoning the linear transverse magnetic field dependence by introducing the sextupole component in the permanent magnets.
Funding Agency
uthored by Jefferson Science Associates, LLC under U.S. DOE Contract
No. DE-AC05-06OR23177.
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