HALO FORMATION OF THE HIGH INTENSITY BEAMS IN A PERIODIC SOLENOID FOCUSING FIELDS

Abstract

Transport of high-intensity beams over long distances can be restricted by space-charge fields which can lead to the beam emittance growth and particle losses in accelerators. The lost particles cause serious radioactivation of the accelerator structure and disturb the proper propagation of the beam. The space-charge fields can be calculated by using Poisson’s equation from the charge density profile. There are several ways to focus the charged particles in accelerators, but we are going to consider a periodic solenoidal magnetic focusing field. For the Kapchinskij-Vladmirskij (K-V) beams, the space charge field is linear but the envelope can be mismatched and have parametric resonances of the envelope instabilities particularly in periodic solenoid fileds. The perturbed oscillations of the core and test particles can generate resonances following by the halo formations. Also, charge non-uniformity can make halos because of the nonlinear space charge force.