SELF-CONSISTENT SIMULATION STUDIES OF PERIODICALLY FOCUSED INTENSE CHARGED-PARTICLE BEAMS

A self-consistent two-dimensional model is used to investigate intense charged-particle beam propagation through a periodic solenoidal focusing channel, particularly in the regime in which there is a mismatch between the beam and the focusing channel. The present self-consistent studies confirm that mismatched beams exhibit nonlinear reso-nances and chaotic behavior in the envelope evolution, as predicted by an earlier enve-lope analysis [C. Chen and R.C. Davidson, Phys. Rev. Lett. 72, 2195 (1994)]. Transient effects due to emittance growth are studied, and halo formation is investigated. The halo size is estimated. The halo characteristics for a periodic focusing channel are found to be qualitatively the same as those for a uniform focusing channel. A threshold condition is obtained numerically for halo formation in mismatched beams in a uniform focusing channel, which indicates that relative envelope mismatch must be kept well below twenty percent to prevent space-charge-dominated beams from developing halos. PACS numbers: 07.77.+p, 29.27.Eg, 41.75.-i, 52.25.Wz I