The electron accelerator for the AWAKE experiment at CERN

K Pepitone,S Doebert,G Burt,E Chevallay,N Chritin,C Delory,V Fedosseev,Ch Hessler,G Mcmonagle,O Mete,V Verzilov,R Apsimon

doi:10.1016/j.nima.2016.02.025

Abstract

The AWAKE collaboration prepares a proton driven plasma wakefield acceleration experiment using the SPS beam at CERN. A long proton bunch extracted from the SPS interacts with a high power laser and a 10m long rubidium vapour plasma cell to create strong wakefields allowing sustained electron acceleration. The electron bunch to probe these wakefields is supplied by a 20MeV electron accelerator. The electron accelerator consists of an RF-gun and a short booster structure. This electron source should provide beams with intensities between 0.1 and 1nC, bunch lengths between 0.3 and 3ps and an emittance of the order of 2mm mrad. The wide range of parameters should cope with the uncertainties and future prospects of the planned experiments. The layout of the electron accelerator, its instrumentation and beam dynamics simulations are presented.

Highlights

The Advanced Wakefield Experiment (AWAKE) [1] at CERN aims to demonstrate for the first time proton driven plasma wakefield acceleration
It seems, an oblique injection of the electron beam with respect to the proton beam is advantageous to reduce defocusing effects caused by the plasma density transition at the entrance of the plasma cell [4]
The beam line is equipped with diagnostics to measure and optimize the beam parameters after the gun and at the end of the accelerator

Summary

Introduction

The Advanced Wakefield Experiment (AWAKE) [1] at CERN aims to demonstrate for the first time proton driven plasma wakefield acceleration. Beam to match the transverse dimensions of the plasma channel and the wakefield wave It seems, an oblique injection of the electron beam with respect to the proton beam is advantageous to reduce defocusing effects caused by the plasma density transition at the entrance of the plasma cell [4]. The electron accelerator for AWAKE consists of a 2.5 cell RF-gun and a one meter long booster structure both at 3 GHz. A cathode is illuminated with a frequency quadrupled laser pulse which is derived from the main drive laser for the plasma. The operation mode will be a single bunch with a maximum repetition rate of 10 Hz. The SPS extraction rate of the proton beam is 0.14 Hz. The beam line is equipped with diagnostics to measure and optimize the beam parameters after the gun and at the end of the accelerator. Pepitone et al / Nuclear Instruments and Methods in Physics Research A 829 (2016) 73–75

Electron accelerator beam dynamics

Findings

Conclusion