A self-consistent model for emittance growth of mismatched charged particle beams in linear accelerators

This work analyzes the envelope dynamics of a high- intensity charged particle beam focused by constant magnetic field. As known, beams with mismatched envelopes decay into its equilibrium state with a simultaneous increasing of its emittance. This implies that in the stationary regime the beam transverse phase-space is characterized by a tenuous population of high velocity particles surrounding a dense population of low velocity particles. To describe this emittance growth, a test-particle approach has been employed by us to develop a simplified self-consistent macroscopic model. The model has been compared with full N-particle Gauss simulations and the agreement is shown to be quite reasonable.