High-energy betatron source driven by a 4-PW laser with applications to non-destructive imaging

TL;DR

This paper demonstrates a high-energy betatron radiation source driven by a 4-PW laser, capable of non-destructive imaging of dense objects with sub-millimeter resolution, useful for industrial and physics applications.

Contribution

It introduces a compact, high-repetition-rate betatron radiation setup producing MeV photons for detailed non-destructive imaging and diagnostics.

Findings

Radiation spectrum with 515 keV critical energy and 10 mrad divergence.

Successful imaging of dense objects revealing internal structures.

Potential applications in non-destructive testing and high-energy-density physics.

Abstract

Petawatt-class lasers can produce multi-GeV electron beams through laser wakefield electron acceleration. As a by-product, the accelerated electron beams can generate broad synchrotron-like radiation known as betatron radiation. In the present work, we measure the properties of the radiation produced from 2 GeV, 215 pC electron beams, which shows a broad radiation spectrum with a critical energy of 515 keV, extending up to MeV photon energies and 10 mrad divergence. Due to its high energy and flux, such radiation is an ideal candidate for gamma-ray radiography of dense objects. We employed a compact betatron radiation setup operated at relatively high-repetition rates (0.1 Hz) and used it to scan cm-sized objects: a DRAM circuit, BNC and SMA connectors, a padlock and a gas jet nozzle. GEANT4 simulations were carried out to reproduce the radiograph of the gas jet. The setup and the radiation source can reveal the interior structure of the objects at the sub-mm level, proving that it can further be applied to diagnose cracks or holes in various components. The radiation source presented here is a valuable tool for non-destructive inspection and for applications in high-energy-density physics such as nuclear fusion.