title: Nonlinear-resonance analysis of halo formation excited by beam-core oscillation
abstract: The emittance growth and halo formation for a mismatched beam of a one-dimensional Gaussian distribution in a uniform focusing channel were examined by means of a macroparticle simulation. The results were analyzed by isolated nonlinear resonance theory. The second-harmonic resonance driven by beam-core oscillation was both numerically and analytically shown to assume a key role in forming a halo. An analytic estimation of the halo location was explored, and the halo location was proved to correspond to the outer edge of the resonance islands. Nonlinear fields in an actual particle distribution have been shown to significantly affect both the halo's location and size.
authors.affiliation: Department of Energy Science and Engineering, Kyushu University, Fukuoka 812-8581, Japan.
authors.initials: Y
authors.lastname: Shimosaki
authors.initials: K
authors.lastname: Takayama