Tunable, all-optical quasi-monochromatic Thomson X-ray source

TL;DR

This paper presents the first all-laser-driven, tunable, quasi-monochromatic X-ray source based on Thomson backscattering, achieving energy tunability and narrow bandwidth in a compact setup, with ultrashort pulse duration.

Contribution

It demonstrates a novel all-optical, energy-tunable X-ray source with narrow bandwidth using Thomson backscattering from LWFA electron bunches, advancing previous broad-spectrum results.

Findings

X-ray spectra peaked at 5-35 keV with tunable electron energies from 10-50 MeV

Produced few-fs pulse duration X-ray beams

Achieved energy tunability and quasi-monochromatic output

Abstract

Brilliant X-ray sources are of great interest for many research fields from biology via medicine to material research. The quest for a cost-effective, brilliant source with unprecedented temporal resolution has led to the recent realization of various high-intensity-laser-driven X-ray beam sources. Here we demonstrate the first all-laser-driven, energy-tunable and quasi-monochromatic X-ray source based on Thomson backscattering. This is a decisive step beyond previous results, where the emitted radiation exhibited an uncontrolled broad energy distribution. In the experiment, one part of the laser beam was used to drive a few-fs bunch of quasi-monoenergetic electrons from a Laser-Wakefield Accelerator (LWFA), while the remainder was scattered off the bunch in a near-counter-propagating geometry. When the electron energy was tuned from 10-50 MeV, narrow-bandwidth X-ray spectra peaking at 5-35keV were directly measured, limited in photon energy by the sensitivity curve of our X-ray detector. Due to the ultrashort LWFA electron bunches, these beams exhibit few-fs pulse duration.