Direct measurement of focusing fields in active plasma lenses

J.-H Röckemann,L Schaper,W Lauth,K Floettmann,G Boyle,J Van Tilborg,V Libov,G Kube,N Delbos,S Wesch,Philipp Messner ,Wim Leemans ,Stepan Bulanov ,Andreas Maier ,Martin Meisel ,C B Schroeder ,P V Sasorov ,N A Bobrova ,Sarah Barber ,Jens Osterhoff

doi:10.1103/physrevaccelbeams.21.122801

Abstract

Active plasma lenses have the potential to enable broad-ranging applications of plasma-based accelerators owing to their compact design and radially symmetric kT/m-level focusing fields, facilitating beam-quality preservation and compact beam transport. We report on the direct measurement of magnetic field gradients in active plasma lenses and demonstrate their impact on the emittance of a charged particle beam. This is made possible by the use of a well-characterized electron beam with 1.4 mm mrad normalized emittance from a conventional accelerator. Field gradients of up to 823 T/m are investigated. The observed emittance evolution is supported by numerical simulations, which suggest the potential for conservation of the core beam emittance in such a plasma lens setup.

Highlights

Laser wakefield accelerators (LWFAs) allow for the generation of extreme electric fields on the order of 100 GV=m for charged particle acceleration and can deliver beams of sub-μm normalized emittance [1,2], multi-kA peak currents [3], and femtosecond pulse duration [4,5,6]
We report on the direct measurement of magnetic field gradients in active plasma lenses and demonstrate their impact on the emittance of a charged particle beam
In this work we report on a first direct measurement of the magnetic field distribution inside an active plasma lens (APL) and complement these results by experimentally detecting its influence on the emittance of a stable, wellcharacterized electron beam from a conventional accelerator

Summary

Introduction

Laser wakefield accelerators (LWFAs) allow for the generation of extreme electric fields on the order of 100 GV=m for charged particle acceleration and can deliver beams of sub-μm normalized emittance [1,2], multi-kA peak currents [3], and femtosecond pulse duration [4,5,6]. LWFAs have shown the capability to produce multiGeV electron beams in cm-scale structures [7,8,9] Their application to drive compact sources of coherent x-ray beams [10,11] and incoherent MeV photons [12], ultra-fast electron diffraction experiments [13,14], and high-energy particle colliders [15] has been proposed and studied [16,17]. For all these applications small beam emittances are critical. Beam capturing within a few centimeters after the plasma exit is crucial for emittance preservation

Methods

Results

Conclusion