Demonstration of ultra-low emittance beams in a kHz laser wakefield accelerator and application to electron diffraction

TL;DR

This paper demonstrates a compact method to measure ultra-low emittance electron beams from a laser wakefield accelerator and successfully applies these beams to electron diffraction, achieving high-quality diffraction images.

Contribution

It introduces a cost-effective, compact emittance measurement technique for kHz laser wakefield electron beams and demonstrates their application in high-resolution electron diffraction.

Findings

Measured normalized emittance of 124 nm·rad at 2.7 MeV

Achieved clear diffraction peaks from a silicon nano-membrane

Demonstrated practical application of low-emittance beams in electron diffraction

Abstract

We present a compact, cost-effective method for measuring the emittance of kHz-repetition-rate laser-wakefield accelerated electron beams using a permanent solenoid. The measured normalized emittance, $\epsilon_n = 124\,\mathrm{nm \cdot rad}$ ($\simeq 0.04 \pi\,\mathrm{mm \cdot mrad}$) at $2.7\,$MeV, is comparable to that of ultra-low emittance radiofrequency guns used for electron diffraction. Leveraging this low emittance, we successfully applied the electron beam to electron diffraction. We demonstrate diffraction images obtained from a single crystal Silicon nano-membrane sample, clearly resolving diffraction peaks across multiple orders.