First emittance measurement of the beam-driven plasma wakefield accelerated electron beam

TL;DR

This paper reports the first direct measurement of emittance in a beam-driven plasma wakefield accelerator, demonstrating high-quality beam acceleration with minimal emittance growth and energy spread.

Contribution

It presents the first direct emittance measurement of a PWFA beam, showing preserved beam quality after acceleration.

Findings

Final energy spread of 0.2%

Normalized transverse emittance of 3.8 μm

High-quality beam maintained after acceleration

Abstract

Next-generation plasma-based accelerators can push electron beams to GeV energies within centimetre distances. The plasma, excited by a driver pulse, is indeed able to sustain huge electric fields that can efficiently accelerate a trailing witness bunch, which was experimentally demonstrated on multiple occasions. Thus, the main focus of the current research is being shifted towards achieving a high quality of the beam after the plasma acceleration. In this letter we present beam-driven plasma wakefield acceleration experiment, where initially preformed high-quality witness beam was accelerated inside the plasma and characterized. In this experiment the witness beam quality after the acceleration was maintained on high level, with $0.2\%$ final energy spread and $3.8~\mu m$ resulting normalized transverse emittance after the acceleration. In this article, for the first time to our knowledge, the emittance of the PWFA beam was directly measured.