Simplified self-consistent model for emittance growth in charged beams with mismatched envelopes

Abstract

This paper analyzes the envelope dynamics of magnetically focused, high-intensity charged particle beams. As known, mismatched envelopes decay into equilibrium with simultaneous emittance growth. To describe the emittance growth we develop a simplified self-consistent macroscopic model: emittance is evaluated in a partially analytical way which invokes the beam profile, with self-consistency resulting from the inclusion of the emittance growth into the envelope equation. The model is then compared with full N-particle beam simulations and the agreement is shown to be quite reasonable. The model helps to understand the physics of the problem and is computationally faster than full simulations. Other aspects are discussed in the paper.