Effect of pulsed hollow electron-lens operation on the proton beam core in LHC

TL;DR

This paper investigates how pulsed hollow electron-lens operation affects the proton beam core in the LHC, focusing on noise induction and emittance growth during active halo control.

Contribution

It provides simulation-based analysis of the effects of pulsed electron-lens operation on proton beam stability and outlines experimental plans for the LHC.

Findings

Pulsing can induce noise affecting the proton beam core.

Sensitivity to pulsing pattern influences emittance growth.

Preparatory simulations inform upcoming LHC experiments.

Abstract

Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In order to further increase the diffusion rates for a fast halo removal as e.g. desired before the squeeze, the electron lens (e-lens) can be operated in pulsed mode. In case of profile imperfections in the electron beam the pulsing of the e-lens induces noise on the proton beam which can, depending on the frequency content and strength, lead to emittance growth. In order to study the sensitivity to the pulsing pattern and the amplitude, a beam study (machine development MD) at the LHC has been proposed for August 2016 and we present in this note the preparatory simulations and estimates.