Cleaning the beam halo using nonlinear AC magnets

TL;DR

This paper explores using high-order nonlinear AC magnets to selectively remove beam halo in particle accelerators by trapping it into nonlinear resonances and transporting it out of the beam core.

Contribution

It introduces a novel method employing high-order nonlinear AC magnets for beam halo removal, extending previous nonlinear cooling techniques to more realistic 4D phase space scenarios.

Findings

Nonlinear AC magnets can effectively trap beam halo into resonances.

Adiabatic transport can remove halo without affecting the core.

Numerical simulations support the feasibility of the approach.

Abstract

Recently, nonlinear effects have been utilized to cool a special beam represented by an annular distribution in a 2D phase space. This outcome was accomplished using an AC dipole combined with amplitude detuning generated by static nonlinear magnets. In this paper, we investigate a more realistic scenario in which a beam distribution in a 4D phase space includes the presence of a beam halo and demonstrate how the latter can be removed using nonlinear effects. The proposed approach employs high-order nonlinear AC magnets to trap into nonlinear resonances and to perform an adiabatic transport of the beam halo in phase space. Theoretical models will be formulated and examined through numerical simulations to evaluate their efficacy.