Probing the diffusive behaviour of beam-halo dynamics in circular accelerators

TL;DR

This paper introduces a diffusive modeling framework for understanding beam-halo dynamics in circular accelerators, aiming to improve machine protection by accurately measuring diffusion coefficients.

Contribution

It presents a novel diffusive approach based on Nekhoroshev's theorem to model and measure beam-halo dynamics in accelerators.

Findings

Proposed an effective model for beam-halo diffusion

Developed an experimental procedure to measure diffusion coefficients

Enhanced understanding of halo dynamics for machine protection

Abstract

Circular particle accelerators at the energy frontier are based on superconducting magnets that are extremely sensitive to beam losses as these might induce quenches, i.e.\ transitions to the normal-conducting state. Furthermore, the energy stored in the circulating beam is so large that hardware integrity is put in serious danger, and machine protection becomes essential for reaching the nominal accelerator performance. In this challenging context, the beam halo becomes a potential source of performance limitations and its dynamics needs to be understood in detail to assess whether it could be an issue for the accelerator. In this paper, we discuss in detail a novel framework, based on a diffusive approach, to model beam-halo dynamics. The functional form of the optimal estimate of the perturbative series, as given by Nekhoroshev's theorem, is used to provide the functional form of the action diffusion coefficient. The goal is to propose an effective model for the beam-halo dynamics and to devise an efficient experimental procedure to obtain an accurate measurement of the diffusion coefficient.