Scaling method of hot electron temperature using bremsstrahlung spectra

Bremsstrahlung X-rays are generated when the ultra-short ultra-intense laser interacts with solid targets. The transport of hot electrons in solid targets and the generation of bremsstrahlung X-rays were simulated using Monte Carlo method. Simulation results of the bremsstrahlung produced by 1 MeV electrons interacting with targets show that the slopes of high energy part of bremsstrahlung spectra can not be influenced obviously by target thickness and target material. Simulation of Maxwellian distribution and mono-energetic electron beams interacting with a 30 m thick Cu target shows that the bremsstrahlung photon spectra from these two electron sources are in agreement with each other. A scaling method of hot electron temperature according to the slope of high energy part of the bremsstrahlung spectrum is presented. The bremsstrahlung energy and number angular distributions were studied for different hot electron temperatures. The results indicate that the forward peaking trait of angular distributions can be enhanced by increasing the electron temperature, thus another scaling method based on this relation is proposed.