Direct Measurement of Focusing Fields in Active Plasma Lenses

TL;DR

This paper presents the first direct measurements of magnetic focusing fields in active plasma lenses and examines their effects on beam emittance, demonstrating potential for high-gradient focusing in compact accelerator applications.

Contribution

It provides the first direct measurement of magnetic field gradients in active plasma lenses and analyzes their impact on beam emittance using experimental data and simulations.

Findings

Field gradients up to 823 T/m measured

Emittance evolution observed and supported by simulations

Potential for core beam emittance conservation

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.