title: Fundamental limit of nonscaling fixed-field alternating-gradient accelerators.
abstract: Systematic nonlinear space-charge resonances may cause substantial emittance growth in the nonscaling fixed-field alternating-gradient (FFAG) accelerators. To avoid systematic nonlinear space-charge resonances, the phase advance of each nonscaling FFAG cell must avoid pi/2 and pi/3. Using multiparticle numerical simulations, we empirically obtain a minimum tune ramp rate vs the systematic 4th order space-charge resonance strength. We also find that the emittance growth obeys a simple scaling property when the betatron tunes cross the linear half-integer and sum resonances.
authors.affiliation: Department of Physics, Indiana University, Bloomington, Indiana 47405, USA and GSI, Darmstadt, D64291, Germany.
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee