Comparison of measured and calculated x-ray and hot-electron production in short-pulse laser-solid interactions at moderate intensities

Ultrashort pulse laser-solid interaction experiments with $4\times {10}^{16}\hspace{0.5em}{\mathrm{W}/\mathrm{c}\mathrm{m}}^2,$120 fs, $45°$ incidence angle, p-polarized pulses are theoretically analyzed with the help of $1\frac{1}{2}$-dimensional $(1\mathrm{}\frac{1}{2}$ D) particle-in-cell (PIC) simulations. The laser impinges upon preformed plasmas with a precisely controlled density-gradient scale-length. PIC electron distribution functions are used as an input to 3D Monte Carlo simulations to interpret measured electron distributions and $K\alpha$ radiation emission. Satisfactory agreement between the experimental and simulation results is obtained for the measured absorption coefficient, the energy distribution of the back-scattered hot electrons, the hot-electron temperature in the bulk of the target, and the $K\alpha$ yield, when the preplasma scale-length is varied.