The effect of nonlinear transport on beam halo formation

Halo formation is an important issue in intense charged particle beams because the loss of halo particles can lead to radioactivation of the accelerator. In this paper, we investigate the influence of the addition of nonlinear terms to the linear focusing as a possible mechanism to control halo formation. With nonlinear focusing, the core oscillations can no longer be described by an envelope equation. The use of more self-consistent models like particle-in-cell codes become necessary. Using a one dimensional particle-in cell code, we make comparisons between beams with linear and nonlinear focusing. We also discuss the physical parameters, that are set before launching the beam in order to make such comparisons