Energy loss of a high-charge bunched electron beam in plasma: Analysis

N Barov,J B Rosenzweig,M C Thompson,R B Yoder

doi:10.1103/physrevstab.7.061301

Abstract

There has been much interest in the blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high fields and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity. The physical basis for this effect is discussed, as are deviations from linear behavior observed in simulations with finite length beams.

Highlights

The transfer of energy from short, intense electron beams to collective electron plasma oscillations is a critical component of the advanced, high-gradient acceleration scheme known as the plasma wakefield accelerator (PWFA) [1,2,3,4]
In the highly nonlinear ‘‘blowout’’ regime [4], the plasma electrons are ejected from the channel of the intense driving electron beam, resulting in an electron-rarefied region with excellent quality transverse and longitudinal fields
[6 –9] that the beam energy loss rate in the PWFA blowout regime scales as 2 z when the plasma density is adjusted in order to keep kp z constant

Summary

INTRODUCTION

The transfer of energy from short, intense electron beams to collective electron plasma oscillations is a critical component of the advanced, high-gradient acceleration scheme known as the plasma wakefield accelerator (PWFA) [1,2,3,4]. Despite the lack of analytical models for the nonlinear plasma response, it has been noted in a number of studies [6 –9] that the beam energy loss rate in the PWFA blowout regime scales as 2 z when the plasma density is adjusted in order to keep kp z constant. This prediction has led to a number of experiments that employ bunch compressors in order to decrease the electron bunch length z , dramatically increasing the transfer of beam energy to the plasma. This discussion of the plasma electrodynamic response produces comparisons with both the linear regime of the PWFA, as well as with the nonlinear regime of the laser-plasma interaction

PARTICLE-IN-CELL SIMULATIONS OF AN

NONLINEAR PLASMA EXCITATION BY A

DISCUSSION AND CONCLUSIONS