Isochronous (CW) Non-Scaling FFAGs: Design and Simulation
Abstract
The drive for higher beam power, high duty cycle,
and reliable beams at reasonable cost has focused
international attention and design effort on fixed field
accelerators, notably Fixed-Field Alternating Gradient accelerators
(FFAGs). High-intensity GeV proton drivers encounter duty
cycle and space-charge limits in the synchrotron and
machine size concerns in the weaker-focusing cyclotrons.
A 10-20 MW proton driver is challenging, if even technically
feasible, with conventional accelerators - with the possible
exception of a SRF linac, which has a large associated cost
and footprint. Recently, the concept of isochronous orbits has
been explored and developed for nonscaling FFAGs using
powerful new methodologies in FFAG accelerator design and
simulation. The property of isochronous orbits enables the
simplicity of fixed RF and, by tailoring a nonlinear radial
field profile, the FFAG can remain isochronous beyond the
energy reach of cyclotrons, well into the relativistic regime.
With isochronous orbits, the machine proposed here has the
high average current advantage and duty cycle of the cyclotron
in combination with the strong focusing, smaller losses,
and energy variability that are more typical of the synchrotron.
This paper reports on these new advances in FFAG
accelerator technology and presents advanced modeling tools
for fixed-field accelerators unique to the code COSY
INFINITY.
C. Johnstone, M. Berz, K. Makino, P. Snopok,
American Institute of Physics CP 1299 (2011) 682-687
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