title: Effects of resonances on halo formation in high-intensity storage rings.
abstract: Numerical calculations for the Spallation Neutron Source accumulator ring indicate that lattice resonances excited by the space-charge potential can increase a mismatch significantly by deforming the beam distribution in phase space. Hence increased mismatch leads to enhanced envelope oscillations that are driving the 2:1 parametric resonance leading to halo formation, even for initially matched beams. We have observed this behavior for the 2 nu(x) - 2 nu(y) = 0 resonance and for the 4 nu(y) = 23 resonance. This mechanism for halo formation peculiar to rings through resonance driven mismatch is very sensitive to the tunes, which emphasizes the importance of a careful choice of operating point in tune space.
authors.affiliation: SNS Bldg MS-8218, Oak Ridge National Laboratory, 104 Union Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: D
authors.initials: D
authors.lastname: Jeon
authors.forename: J A
authors.initials: JA
authors.lastname: Holmes
authors.forename: V V
authors.initials: VV
authors.lastname: Danilov
authors.forename: J D
authors.initials: JD
authors.lastname: Galambos
authors.forename: D K
authors.initials: DK
authors.lastname: Olsen