T.P. WANGLER (LANL)
Space-charge forces acting in mismatched beams have been identified as a major cause of halo in proton-linac beams. Mismatch excites collective oscillation modes of the beam, which can resonate parametrically with the transverse or longitudinal oscillations of some beam particles, driving those particles to larger amplitudes. Particle-core models make predictions for the halo properties, including approximate scaling formulas for the maximum halo amplitude, which are in good agreement with multiparticle simulations. A beam-halo experiment is being carried out at the LEDA (Low Energy Demonstration Accelerator) facility at Los Alamos, which will address questions about the beam profiles, maximum particle amplitudes, and rms emittance growth associated with the halo.
*Work supported by the U.S. Department of Energy.
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