A symplectic particle-in-cell model for space-charge beam dynamics simulation

TL;DR

This paper introduces a symplectic particle-in-cell model for simulating space-charge effects in high intensity particle accelerators, demonstrating its accuracy and advantages over traditional models in long-term simulations.

Contribution

The paper develops a symplectic PIC model and compares it with existing symplectic gridless and nonsymplectic PIC models, highlighting its improved accuracy and stability.

Findings

Symplectic PIC and gridless models agree closely on emittance growth.

Nonsymplectic PIC results differ but converge with finer step sizes.

Symplectic models are more reliable for long-term simulations.

Abstract

Space-charge effects play an important role in high intensity particle accelerators and were studied using a variety of macroparticle tracking models. In this paper, we propose a symplectic particle-in-cell (PIC) model and compare this model with a recently published symplectic gridless particle model and a conventional nonsymplectic PIC model for long-term space-charge simulation of a coasting beam. Using the same step size and the same number of modes for the space-charge Poisson solver, all three models show qualitatively similar emittance growth evolutions and final phase space shapes in the benchmark examples. Quantitatively, the symplectic PIC and the symplectic gridless particle models agree with each other very well, while the nonsymplectic PIC model yields different emittance growth value. Using finer step size, the emittance growth from the nonsymplectic PIC converges towards that from the symplectic PIC model.