Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator

TL;DR

This paper presents a model predicting electron beam and x-ray properties in a laser wakefield accelerator, optimizing performance by matching plasma length to laser depletion length, resulting in bright x-ray emission.

Contribution

It introduces a model based on plasma bubble oscillations that predicts accelerator performance considering laser self-focusing and compression effects.

Findings

X-ray beam median energy of 20 keV

Over 6×10^8 photons above 1 keV per shot

Peak brightness of 3×10^22 photons s^{-1} mrad^{-2} mm^{-2} (0.1% BW)^{-1}

Abstract

We show that the properties of the electron beam and bright x-rays produced by a laser wakefield accelerator can be predicted if the distance over which the laser self-focuses and compresses prior to self-injection is taken into account. A model based on oscillations of the beam inside a plasma bubble shows that performance is optimised when the plasma length is matched to the laser depletion length. With a 200~TW laser pulse this results in an x-ray beam with median photon energy of \unit[20]{keV}, $> 6\times 10^{8}$ photons above \unit[1]{keV} per shot and a peak brightness of $\unit[3 \times 10^{22}]{photons~s^{-1}mrad^{-2}mm^{-2} (0.1\% BW)^{-1}}$.