Journal Article

Stability of elliptical self-modulating long proton bunches in plasma wakefields

Muggli, P, Welsch, C P, Perera, A

2020

Overview

The AWAKE experiment at CERN recently demonstrated the world's first acceleration of electrons in a proton-driven plasma wakefield accelerator. Such accelerators show great promise for a new generation of linear e-p colliders using 1-10 GV/m accelerating fields. Efficiently driving a wakefield requires 100-fold self-modulation of the 12cm Super Proton Synchrotron (SPS) proton bunch using a plasma-driven process which must be carefully controlled to saturation. Previous works have modelled this process assuming azimuthal symmetry of the transverse spatial and momentum profiles. In this work, 3D particle-in-cell (PIC) simulations with the code QuickPIC are used to model the self-modulation of non-round bunches. We find that asymmetry in the initial seed wakefield leads to the formation of highly asymmetric microbunches which evolve incoherently along the symmetry axes of the initial bunch profile. However, the resonantly-driven accelerating wakefield is highly stable to both focused and astigmatic non-round bunches.

• Publisher: IOP Publishing
• Subject: Asymmetry / Modulation / Particle in cell technique / Physics / Protons / Symmetry / Synchrotrons