Bremsstrahlung gamma-ray source and gamma radiography based on laser-triggered electron acceleration in the regime of relativistic self-trapping of light

Abstract: The XCELS infrastructure is capable of providing a breakthrough in creating a record-breaking high-power source of gamma radiation using laser-accelerated electron beams, which is substantiated by the numerical simulation of the action of a short XCELS laser pulse on low-density targets and by calculating the bremsstrahlung generated by an electron bunch in a converter target to produce a high-power gamma-ray pulse. The high efficiency of generating a record number of photons of multi-MeV energy with a huge peak gamma-ray flux is due to the use of the relativistic self-trapping of a laser pulse as a driver of such wake acceleration of electrons, which ensures the achievement of a maximum charge of multi-MeV of electrons and the maximum conversion efficiency of laser energy in near-critical density targets. The possibility of converting up to 8% of laser energy into the energy of a beam of gamma-ray photons (with an energy of more than 1 MeV) and the prospects for using the resulting source for deep gamma radiography in a single laser shot are demonstrated. The latter is also substantiated by a numerical experiment on obtaining gamma-ray images of dense hidden objects with a currently record-breaking shielding thickness (up to 400 mm of iron, which corresponds to a linear density of 320 g·cm^–2) with good contrast (high spatial resolution).

Keywords: laser electron source, bremsstrahlung, high-power gamma-ray pulses, deep gamma radiography.