Acceleration in Vertical Orbit Excursion FFAGs with Edge Focussing

FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field superconducting magnets.  They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure.  Edge focussing can provide an alternating gradient within each magnet, thus reducing the ring circumference.  Like spiral scaling horizontal FFAGs (but not non-scaling ones) the machine has fixed tunes and no intrinsic limitation on momentum range.  Rings to accelerate the 800MeV beam from the ISIS proton synchrotron are investigated, in terms of both magnet field geometry and longitudinal behaviour during acceleration with space charge.  The 12GeV ring produces an output power of at least 2.18MW.


----- IPAC'12 abstract:

Vertical Orbit Excursion FFAG Accelerators with Edge Focussing

FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for the magnets in fixed-field machines.  They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure.  The end fields of such magnets with edge angles provide an alternating gradient without the need for reverse bends, thus reducing the machine circumference.  Similarly to spiral scaling horizontal FFAGs (but unlike non-scaling versions), the machine has fixed tunes and no intrinsic limitation on momentum range.  Rings capable of boosting the 150mm.mrad geometric emittance beam from the ISIS proton synchrotron to 3, 5 and 12GeV using superconducting magnets are presented, the latter corresponding to 2.5MW beam power.