Effects of resonances on halo formation in high-intensity storage rings.
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.
Jeon
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SNS Bldg MS-8218, Oak Ridge National Laboratory, 104 Union Valley Road, Oak Ridge, Tennessee 37831, USA.
Holmes
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Danilov
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Galambos
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Olsen
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