Bremsstrahlung production with high-intensity laser matter interactions and applications

In the last decade an evolution of experimental relativistic laser-plasma physics has led to highly sophisticated lasers, which are now able to generate ultra short pulses and can be focused to intensities in excess of 10²¹ W cm⁻², with more than 500 J on target. In the intense electric field of the laser focus, plasma with temperatures greater than 10 billion degrees can be generated. The laser interactions with solid or gas targets can generate collimated beams of highly energetic electrons and ions. Experiments utilizing high-intensity laser systems turn out to be an interesting and versatile source for radiation, high-energy particles and nuclear reactions, without recourse to large-scale facilities such as nuclear reactors or particle accelerators. The possibility of accelerating electrons to energies over 200 MeV in such early experiments led to the utilization of high-energy bremsstrahlung radiation in order to investigate laser-induced gamma reactions. Many experiments of this type have been reported in several laboratories worldwide. However, to our knowledge, no dedicated investigations have been reported with respect to the characterization of the generated bremsstrahlung in such experiments. As it is not experimentally feasible to measure directly a bremsstrahlung spectrum, we report in the present paper on a dedicated series of calculations on the generated bremsstrahlung distributions from two experimental electron spectra measured using the giant pulse VULCAN laser and a gas jet target. Potential applications are also investigated.