Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma

TL;DR

This paper demonstrates a method to control and enhance the self-modulation of a relativistic proton bunch in plasma by seeding it with wakefields driven by a preceding electron bunch, improving reproducibility and growth.

Contribution

It introduces a novel seeding technique using an electron bunch to control and amplify proton bunch self-modulation in plasma.

Findings

Seeding improves SM growth and reproducibility.

Wakefield amplitude is controlled by electron bunch charge.

SM growth rate depends on proton bunch charge.

Abstract

A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.